smarty/docs/programmers.sgml

  <part id="smarty.for.programmers">
   <title>Smarty For Programmers</title>


	<chapter id="smarty.constants">
	 <title>Constants</title>
	 <para></para>

	 <sect1 id="constant.smarty.dir">
      <title>SMARTY_DIR</title>
      <para>
       This should be the full system path to the location of the Smarty
       class files. If this is not defined, then Smarty will attempt to
       determine the appropriate value automatically. If defined, the path
       must end with a slash.
      </para>
      <example>
       <title>SMARTY_DIR</title>
       <programlisting>
// set path to Smarty directory
define("SMARTY_DIR","/usr/local/lib/php/Smarty/");

require_once(SMARTY_DIR."Smarty.class.php");</programlisting>
      </example>
	 </sect1>
	</chapter>

    <chapter id="api.variables">
     <title>Variables</title>

     <sect1 id="variable.template.dir">
      <title>$template_dir</title>
      <para>
       This is the name of the default template directory. If you do
       not supply a resource type when including files, they will be
       found here. By default this is "./templates", meaning that it
       will look for the templates directory in the same directory as
       the executing php script.
      </para>
	   <note>
		   <title>Technical Note</title>
		   <para>
    	   It is not recommended to put this directory under
    	   the web server document root.
    	   </para>
	  </note>
     </sect1>		
     <sect1 id="variable.compile.dir">
      <title>$compile_dir</title>
      <para>
       This is the name of the directory where compiled templates are
       located. By default this is "./templates_c", meaning that it
       will look for the compile directory in the same directory as
       the executing php script.
      </para>
	 <note>
	 <title>Technical Note</title>
	 <para>
       This setting must be either a relative or
       absolute path. include_path is not used for writing files.
      </para>
	 </note>
	 <note>
	 <title>Technical Note</title>
	 <para>
       It is not recommended to put this directory under
       the web server document root.
      </para>
	 </note>
     </sect1>
     <sect1 id="variable.config.dir">
      <title>$config_dir</title>
      <para>
       This is the directory used to store config files used in the
       templates. Default is "./configs", meaning that it will look
       for the configs directory in the same directory as the
       executing php script.
      </para>
	 <note>
	 <title>Technical Note</title>
	 <para>
       It is not recommended to put this directory under
       the web server document root.
      </para>
	 </note>
     </sect1>
     <sect1 id="variable.plugins.dir">
      <title>$plugins_dir</title>
      <para>
	   This is the directories where Smarty will look for the plugins that it
	   needs. Default is "plugins" under the SMARTY_DIR. If you supply a
	   relative path, Smarty will first look under the SMARTY_DIR, then
	   relative to the cwd (current working directory), then relative to each
	   entry in your PHP include path.
      </para>
	  <note>
	  <title>Technical Note</title>
	  <para>
	  For best performance, do not setup your plugins_dir to have to use the
	  PHP include path. Use an absolute pathname, or a path relative to
	  SMARTY_DIR or the cwd.
	  </para>
	  </note>
     </sect1>
     <sect1 id="variable.debugging">
      <title>$debugging</title>
      <para>
       This enables the <link
        linkend="chapter.debugging.console">debugging console</link>.
       The console is a javascript window that informs you of the
       included templates and assigned variables for the current
       template page.
      </para>
     </sect1>
     <sect1 id="variable.debug.tpl">
      <title>$debug_tpl</title>
      <para>
	   This is the name of the template file used for the debugging console. By
	   default, it is named debug.tpl and is located in the <link
	   linkend="constant.smarty.dir">SMARTY_DIR</link>.
      </para>
     </sect1>
     <sect1 id="variable.debugging.ctrl">
      <title>$debugging_ctrl</title>
      <para>
       This allows alternate ways to enable debugging. NONE means no
       alternate methods are allowed. URL means when the keyword
       SMARTY_DEBUG is found in the QUERY_STRING, debugging is enabled
       for that invocation of the script. If $debugging is true, this
       value is ignored.
      </para>
     </sect1>
     <sect1 id="variable.global.assign">
      <title>$global_assign</title>
      <para>
       This is a list of variables that are always implicitly assigned
       to the template engine. This is handy for making global
       variables or server variables available to all templates
       without having to manually assign them. Each element in the
       $global_assign should be either a name of the global variable,
       or a key/value pair, where the key is the name of the global
       array and the value is the array of variables to be assigned
       from that global array. $SCRIPT_NAME is globally assigned by
       default from $HTTP_SERVER_VARS.
      </para>
	 <note>
	 <title>Technical Note</title>
	 <para>
       Server variables can be accessed through the
       $smarty variable, such as {$smarty.server.SCRIPT_NAME}. See the
       section on the
       <link linkend="language.variables.smarty">$smarty</link> variable.
      </para>
	 </note>
     </sect1>
     <sect1 id="variable.undefined">
      <title>$undefined</title>
      <para>
       This sets the value of $undefined for Smarty, default is null.
       Currently this is only used to set undefined variables in
       $global_assign to a default value.
      </para>
     </sect1>
     <sect1 id="variable.autoload.filters">
      <title>$autoload_filters</title>
      <para>
       If there are some filters that you wish to load on every template
       invocation, you can specify them using this variable and Smarty will
       automatically load them for you. The variable is an associative array
       where keys are filter types and values are arrays of the filter
       names. For example:
       <informalexample>
        <programlisting>
$smarty-&gt;autoload_filters = array('pre' =&gt; array('trim', 'stamp'),
                                  'output' => array('convert')); 
        </programlisting>
       </informalexample> 
      </para>
     </sect1>
     <sect1 id="variable.compile.check">
      <title>$compile_check</title>
      <para>
	   Upon each invocation of the PHP application, Smarty tests to see if the
	   current template has changed (different time stamp) since the last time
	   it was compiled. If it has changed, it recompiles that template. If the
	   template has not been compiled, it will compile regardless of this
	   setting. By default this variable is set to true. Once an application is
	   put into production (templates won't be changing), the compile_check
	   step is no longer needed. Be sure to set $compile_check to "false" for
	   maximal performance. Note that if you change this to "false" and a
	   template file is changed, you will *not* see the change since the
	   template will not get recompiled. If caching is enabled and
	   compile_check is enabled, then the cache files will get regenerated if
	   an involved template file or config file was updated. See <link
	   linkend="variable.force.compile">$force_compile</link> or <link
	   linkend="api.clear.compiled.tpl">clear_compiled_tpl</link>.
      </para>
     </sect1>
     <sect1 id="variable.force.compile">
      <title>$force_compile</title>
      <para>
       This forces Smarty to (re)compile templates on every
       invocation. This setting overrides $compile_check. By default
       this is disabled. This is handy for development and debugging.
       It should never be used in a production environment. If caching
       is enabled, the cache file(s) will be regenerated every time.
      </para>
     </sect1>
     <sect1 id="variable.caching">
      <title>$caching</title>
      <para>
	   This tells Smarty whether or not to cache the output of the templates.
	   By default this is set to 0, or disabled. If your templates generate
	   redundant redundant content, it is advisable to turn on caching. This
	   will result in significant performance gains. You can also have multiple
	   caches for the same template. A value of 1 or 2 enables caching. 1 tells
	   Smarty to use the current $cache_lifetime variable to determine if the
	   cache has expired. A value of 2 tells Smarty to use the cache_lifetime
	   value at the time the cache was generated. This way you can set the
	   cache_lifetime just before fetching the template to have granular
	   control over when that particular cache expires. See also <link
	   linkend="api.is.cached">is_cached</link>.
      </para>
      <para>
	   If $compile_check is enabled, the cached content will be regenerated if
	   any of the templates or config files that are part of this cache are
	   changed. If $force_compile is enabled, the cached content will always be
	   regenerated.
      </para>
     </sect1>
     <sect1 id="variable.cache.dir">
      <title>$cache_dir</title>
      <para>
       This is the name of the directory where template caches are
       stored. By default this is "./cache", meaning that it will look
       for the cache directory in the same directory as the executing
       php script. You can also use your own custom cache handler
       function to control cache files, which will ignore this
       setting.
      </para>
	  <note>
	  <title>Technical Note</title>
	  <para>
       This setting must be either a relative or
       absolute path. include_path is not used for writing files.
      </para>
	  </note>
	  <note>
		  <title>Technical Note</title>
		  <para>
    	   It is not recommended to put this directory under
    	   the web server document root.
    	  </para>
	  </note>
     </sect1>
     <sect1 id="variable.cache.lifetime">
      <title>$cache_lifetime</title>
      <para>
	   This is the length of time in seconds that a template cache is valid.
	   Once this time has expired, the cache will be regenerated. $caching must
	   be set to "true" for $cache_lifetime to have any purpose. A value of -1
	   will force the cache to never expire. A value of 0 will cause the cache
	   to always regenerate (good for testing only, to disable caching a more
	   efficient method is to set <link
	   linkend="variable.caching">$caching</link> = false.)
      </para>
	  <para>
	   If <link linkend="variable.force.compile">$force_compile</link> is
	   enabled, the cache files will be regenerated every time, effectively
	   disabling caching. You can clear all the cache files with the <link
	   linkend="api.clear.all.cache">clear_all_cache()</link> function, or
	   individual cache files (or groups) with the <link
	   linkend="api.clear.cache">clear_cache()</link> function.
	  </para>
	  <note>
	  <title>Technical Note</title>
	  <para>
	  If you want to give certain templates their own cache lifetime, you could
	  do this by setting <link linkend="variable.caching">$caching</link> = 2,
	  then set $cache_lifetime to a unique value just before calling display()
	  or fetch().
	  </para>
	  </note>
     </sect1>
     <sect1 id="variable.cache.handler.func">
      <title>$cache_handler_func</title>
      <para>
       You can supply a custom function to handle cache files instead
       of using the built-in method using the $cache_dir. See the
       custom cache handler function section for details.
      </para>
     </sect1>
     <sect1 id="variable.cache.modified.check">
      <title>$cache_modified_check</title>
      <para>
       If set to true, Smarty will respect the If-Modified-Since
       header sent from the client. If the cached file timestamp has
       not changed since the last visit, then a "304 Not Modified"
       header will be sent instead of the content. This works only on
       cached content without <command>insert</command> tags.
      </para>
     </sect1>
     <sect1 id="variable.config.overwrite">
      <title>$config_overwrite</title>
      <para>
       If set to true, variables read in from config files will overwrite each
	   other. Otherwise, the variables will be pushed onto an array. This is
	   helpful if you want to store arrays of data in config files, just list
	   each element multiple times. true by default.
      </para>
     </sect1>
     <sect1 id="variable.config.booleanize">
      <title>$config_booleanize</title>
      <para>
	   If set to true, config file values of on/true/yes and off/false/no get
	   converted to boolean values automatically. This way you can use the
	   values in the template like so: {if #foobar#} ... {/if}. If foobar was
	   on, true or yes, the {if} statement will execute. true by default.
      </para>
     </sect1>
     <sect1 id="variable.config.read.hidden">
      <title>$config_read_hidden</title>
      <para>
	   If set to true, hidden sections (section names beginning with a period)
	   in config files can be read from templates. Typically you would leave
	   this false, that way you can store sensitive data in the config files
	   such as database parameters and not worry about the template loading
	   them. false by default.
	   </para>
     </sect1>
     <sect1 id="variable.config.fix.newlines">
      <title>$config_fix_newlines</title>
      <para>
	   If set to true, mac and dos newlines (\r and \r\n) in config files are
	   converted to \n when they are parsed. true by default.
	   </para>
     </sect1>
     <sect1 id="variable.default.template.handler.func">
      <title>$default_template_handler_func</title>
      <para>
       This function is called when a template cannot be obtained from
       its resource.
      </para>
     </sect1>
     <sect1 id="variable.php.handling">
      <title>$php_handling</title>
      <para>
       This tells Smarty how to handle PHP code embedded in the
       templates. There are four possible settings, default being
       SMARTY_PHP_PASSTHRU. Note that this does NOT affect php code
       within <link linkend="language.function.php">{php}{/php}</link>
       tags in the template.
      </para>    
      <itemizedlist>
       <listitem><para>SMARTY_PHP_PASSTHRU - Smarty echos tags as-is.</para></listitem>
       <listitem><para>SMARTY_PHP_QUOTE - Smarty quotes the tags as
         html entities.</para></listitem>
       <listitem><para>SMARTY_PHP_REMOVE - Smarty removes the tags from
         the templates.</para></listitem>
       <listitem><para>SMARTY_PHP_ALLOW - Smarty will execute the tags
         as PHP code.</para></listitem>
      </itemizedlist>
      <para>
       NOTE: Embedding PHP code into templates is highly discouraged.
       Use <link linkend="language.custom.functions">custom functions</link> or
       <link linkend="language.modifiers">modifiers</link> instead.
      </para>
     </sect1>
     <sect1 id="variable.security">
      <title>$security</title>
      <para>
       $security true/false, default is false. Security is good for
       situations when you have untrusted parties editing the templates
       (via ftp for example) and you want to reduce the risk of system
       security compromises through the template language. Turning on
       security enforces the following rules to the template language,
       unless specifially overridden with $security_settings:
      </para>
      <itemizedlist>
       <listitem><para>If $php_handling is set to SMARTY_PHP_ALLOW, this is
         implicitly changed to SMARTY_PHP_PASSTHRU</para></listitem>
       <listitem><para>PHP functions are not allowed in IF statements,
         except those specified in the $security_settings</para></listitem>
       <listitem><para>templates can only be included from directories
         listed in the $secure_dir array</para></listitem>
       <listitem><para>local files can only be fetched from directories
         listed in the $secure_dir array using {fetch}</para></listitem>
       <listitem><para>{php}{/php} tags are not allowed</para></listitem>
       <listitem><para>PHP functions are not allowed as modifiers, except
         those specified in the $security_settings</para></listitem>
      </itemizedlist>
     </sect1>
     <sect1 id="variable.secure.dir">
      <title>$secure_dir</title>
      <para>
       This is an array of all local directories that are considered
       secure. {include} and {fetch} use this when security is enabled.
      </para>
     </sect1>
     <sect1 id="variable.security.settings">
      <title>$security_settings</title>
      <para>
       These are used to override or specify the security settings when
       security is enabled. These are the possible settings:
      </para>
      <itemizedlist>
       <listitem><para>PHP_HANDLING - true/false. If set to true, the
         $php_handling setting is not checked for security.</para></listitem>
       <listitem><para>IF_FUNCS - This is an array of the names of permitted
         PHP functions in IF statements.</para></listitem>
       <listitem><para>INCLUDE_ANY - true/false. If set to true, any
         template can be included from the file system, regardless of the
         $secure_dir list.</para></listitem>
       <listitem><para>PHP_TAGS - true/false. If set to true, {php}{/php}
         tags are permitted in the templates.</para></listitem>
       <listitem><para>MODIFIER_FUNCS - This is an array of the names of permitted
         PHP functions used as variable modifiers.</para></listitem>
      </itemizedlist>
     </sect1>
     <sect1 id="variable.trusted.dir">
      <title>$trusted_dir</title>
      <para>
	   $trusted_dir is only for use when $security is enabled. This is an array
	   of all directories that are considered trusted. Trusted directories are
	   where you keep php scripts that are executed directly from the templates
	   with <link linkend="language.function.include.php">{include_php}</link>.
      </para>
     </sect1>
     <sect1 id="variable.left.delimiter">
      <title>$left_delimiter</title>
      <para>
       This is the left delimiter used by the template language.
       Default is "{".			
      </para>
     </sect1>
     <sect1 id="variable.right.delimiter">
      <title>$right_delimiter</title>
      <para>
       This is the right delimiter used by the template language.
       Default is "}".			
      </para>
     </sect1>
     <sect1 id="variable.compiler.class">
      <title>$compiler_class</title>
      <para>
       Specifies the name of the compiler class that Smarty will use
       to compile the templates. The default is 'Smarty_Compiler'. For
       advanced users only.
      </para>
     </sect1>
     <sect1 id="variable.request.vars.order">
      <title>$request_vars_order</title>
      <para>
       The order in which request variables are registered, similar to
       variables_order in php.ini
      </para>
     </sect1>
     <sect1 id="variable.compile.id">
      <title>$compile_id</title>
      <para>
	   Persistant compile identifier. As an alternative to passing the same
	   compile_id to each and every function call, you can set this compile_id
	   and it will be used implicitly thereafter.
      </para>
     </sect1>
     <sect1 id="variable.use.sub.dirs">
      <title>$use_sub_dirs</title>
      <para>
	  Set this to false if your PHP environment does not allow the creation of
	  sub directories by Smarty. Sub directories are more efficient, so use them
	  if you can.
      </para>
     </sect1>
     <sect1 id="variable.default.modifiers">
      <title>$default_modifiers</title>
      <para>
	  This is an array of modifiers to implicitly apply to every variable in a
	  template. For example, to HTML-escape every variable by default, use
	  array('escape:"htmlall"'); To make a variable exempt from default
	  modifiers, pass the special "nodefaults" modifier to it, such as
	  {$var|nodefaults}.
      </para>
     </sect1>
    </chapter>

   <chapter id="api.functions">
     <title>Methods</title>
        <sect1 id="api.append">
         <title>append</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>append</function></funcdef>
           <paramdef>mixed <parameter>var</parameter></paramdef>
          </funcprototype>
          <funcprototype>
           <funcdef>void <function>append</function></funcdef>
           <paramdef>string <parameter>varname</parameter></paramdef>
           <paramdef>mixed <parameter>var</parameter></paramdef>
          </funcprototype>
          <funcprototype>
           <funcdef>void <function>append</function></funcdef>
           <paramdef>string <parameter>varname</parameter></paramdef>
           <paramdef>mixed <parameter>var</parameter></paramdef>
           <paramdef>boolean <parameter>merge</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
		  This is used to append an element to an assigned array. If you append
		  to a string value, it is converted to an array value and then
		  appended to. You can explicitly pass name/value pairs, or associative
		  arrays containing the name/value pairs. If you pass the optional third
		  parameter of true, the value will be merged with the current array
		  instead of appended.
         </para>
		 <note>
		 <title>Technical Note</title>
		 <para>
		 The merge parameter respects array keys, so if you merge two
		 numerically indexed arrays, they may overwrite each other or result in
		 non-sequential keys. This is unlike the array_merge() function of PHP
		 which wipes out numerical keys and renumbers them.
		 </para>
		 </note>
         <example>
          <title>append</title>
          <programlisting>
// passing name/value pairs
$smarty->append("Name","Fred");
$smarty->append("Address",$address);

// passing an associative array
$smarty->append(array("city" => "Lincoln","state" => "Nebraska"));</programlisting>
</example>
		</sect1>
     <sect1 id="api.append.by.ref">
      <title>append_by_ref</title>
      <funcsynopsis>
       <funcprototype>
        <funcdef>void <function>append_by_ref</function></funcdef>
        <paramdef>string <parameter>varname</parameter></paramdef>
        <paramdef>mixed <parameter>var</parameter></paramdef>
       </funcprototype>
       <funcprototype>
        <funcdef>void <function>append_by_ref</function></funcdef>
        <paramdef>string <parameter>varname</parameter></paramdef>
        <paramdef>mixed <parameter>var</parameter></paramdef>
        <paramdef>boolean <parameter>merge</parameter></paramdef>
       </funcprototype>
      </funcsynopsis>
      <para>
	   This is used to append values to the templates by reference.
	   If you append a variable by reference then change its
       value, the appended value sees the change as well. For objects, 
       append_by_ref() also avoids an in-memory copy of the appended object.
       See the PHP manual on variable referencing for an in-depth
	   explanation. If you pass the optional third parameter of true,
       the value will be merged with the current array instead of appended.
      </para>
	  <note>
	  <title>Technical Note</title>
	  <para>
	  The merge parameter respects array keys, so if you merge two
	  numerically indexed arrays, they may overwrite each other or result in
	  non-sequential keys. This is unlike the array_merge() function of PHP
	  which wipes out numerical keys and renumbers them.
	  </para>
	  </note>
      <example>
       <title>append_by_ref</title>
       <programlisting>
// appending name/value pairs
$smarty->append_by_ref("Name",$myname);
$smarty->append_by_ref("Address",$address);</programlisting>
</example>
		</sect1>
     <sect1 id="api.assign">
      <title>assign</title>
      <funcsynopsis>
       <funcprototype>
        <funcdef>void <function>assign</function></funcdef>
        <paramdef>mixed <parameter>var</parameter></paramdef>
       </funcprototype>
       <funcprototype>
        <funcdef>void <function>assign</function></funcdef>
        <paramdef>string <parameter>varname</parameter></paramdef>
        <paramdef>mixed <parameter>var</parameter></paramdef>
       </funcprototype>
      </funcsynopsis>
      <para>
       This is used to assign values to the templates. You can
       explicitly pass name/value pairs, or associative arrays
       containing the name/value pairs.
      </para>
      <example>
       <title>assign</title>
       <programlisting>
// passing name/value pairs
$smarty->assign("Name","Fred");
$smarty->assign("Address",$address);

// passing an associative array
$smarty->assign(array("city" => "Lincoln","state" => "Nebraska"));</programlisting>
</example>
		</sect1>
     <sect1 id="api.assign.by.ref">
      <title>assign_by_ref</title>
      <funcsynopsis>
       <funcprototype>
        <funcdef>void <function>assign_by_ref</function></funcdef>
        <paramdef>string <parameter>varname</parameter></paramdef>
        <paramdef>mixed <parameter>var</parameter></paramdef>
       </funcprototype>
      </funcsynopsis>
      <para>
	   This is used to assign values to the templates by reference instead of
	   making a copy. See the PHP manual on variable referencing for an explanation.
      </para>
	  <note>
	  <title>Technical Note</title>
	  <para>
	   This is used to assign values to the templates by reference.
	   If you assign a variable by reference then change its
       value, the assigned value sees the change as well. For objects, 
       assign_by_ref() also avoids an in-memory copy of the assigned object.
       See the PHP manual on variable referencing for an in-depth
	   explanation.
	  </para>
	  </note>
      <example>
       <title>assign_by_ref</title>
       <programlisting>
// passing name/value pairs
$smarty->assign_by_ref("Name",$myname);
$smarty->assign_by_ref("Address",$address);</programlisting>
</example>
		</sect1>
		<sect1 id="api.clear.all.assign">
			<title>clear_all_assign</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>clear_all_assign</function></funcdef>
				<paramdef><parameter></parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
				This clears the values of all assigned variables.
			</para>
<example>
<title>clear_all_assign</title>
<programlisting>
// clear all assigned variables
$smarty->clear_all_assign();</programlisting>
</example>
		</sect1>
		<sect1 id="api.clear.all.cache">
			<title>clear_all_cache</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>clear_all_cache</function></funcdef>
				<paramdef>int <parameter>expire time</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
				This clears the entire template cache. As an optional
				parameter, you can supply a minimum age in seconds the cache
				files must be before they will get cleared.
			</para>
<example>
<title>clear_all_cache</title>
<programlisting>
// clear the entire cache
$smarty->clear_all_cache();</programlisting>
</example>
		</sect1>
		<sect1 id="api.clear.assign">
			<title>clear_assign</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>clear_assign</function></funcdef>
				<paramdef>string <parameter>var</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
				This clears the value of an assigned variable. This
                can be a single value, or an array of values.
			</para>
<example>
<title>clear_assign</title>
<programlisting>
// clear a single variable
$smarty->clear_assign("Name");

// clear multiple variables
$smarty->clear_assign(array("Name","Address","Zip"));</programlisting>
</example>
		</sect1>
		<sect1 id="api.clear.cache">
			<title>clear_cache</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>clear_cache</function></funcdef>
				<paramdef>string <parameter>template</parameter></paramdef>
				<paramdef>string <parameter><optional>cache id</optional></parameter></paramdef>
				<paramdef>string <parameter><optional>compile id</optional></parameter></paramdef>
				<paramdef>int <parameter><optional>expire time</optional></parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
				This clears the cache for a specific template. If you have
				multiple caches for this template, you can clear a specific
				cache by supplying the cache id as the second parameter. You
				can also pass a compile id as a third parameter. You can "group"
				templates together so they can be removed as a group. See the
				<link linkend="caching">caching section</link> for more
				information. As an optional fourth parameter, you can supply a
				minimum age in seconds the cache file must be before it will
				get cleared.
			</para>
<example>
<title>clear_cache</title>
<programlisting>
// clear the cache for a template
$smarty->clear_cache("index.tpl");

// clear the cache for a particular cache id in an multiple-cache template
$smarty->clear_cache("index.tpl","CACHEID");</programlisting>
</example>
		</sect1>
		<sect1 id="api.clear.compiled.tpl">
			<title>clear_compiled_tpl</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>clear_compiled_tpl</function></funcdef>
				<paramdef>string <parameter>tpl_file</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
			This clears the compiled version of the specified template
			resource, or all compiled template files if one is not specified.
			This function is for advanced use only, not normally needed.
			</para>
<example>
<title>clear_compiled_tpl</title>
<programlisting>
// clear a specific template resource
$smarty->clear_compiled_tpl("index.tpl");

// clear entire compile directory
$smarty->clear_compiled_tpl();</programlisting>
</example>
		</sect1>
		<sect1 id="api.clear.config">
			<title>clear_config</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>clear_config</function></funcdef>
				<paramdef>string <parameter><optional>var</optional></parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
			This clears all assigned config variables. If a variable name is
			supplied, only that variable is cleared.
			</para>
<example>
<title>clear_config</title>
<programlisting>
// clear all assigned config variables.
$smarty->clear_config();

// clear one variable
$smarty->clear_config('foobar');</programlisting>
</example>
		</sect1>
		<sect1 id="api.config.load">
			<title>config_load</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>config_load</function></funcdef>
				<paramdef>string <parameter>file</parameter></paramdef>
				<paramdef>string <parameter><optional>section</optional></parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
			This loads config file data and assigns it to the template. This
			works identical to the template <link
			linkend="language.function.config.load">config_load</link>
			function.
			</para>
		  <note>
		  <title>Technical Note</title>
    	  <para>
		   As of Smarty 2.4.0, assigned template variables are kept across
		   invocations of fetch() and display(). Config vars loaded from
		   config_load() are always global scope. Config files are also
		   compiled for faster execution, and respect the <link
		   linkend="variable.force.compile">force_compile</link> and <link
		   linkend="variable.compile.check">compile_check</link> settings.
    	  </para>
		  </note>
<example>
<title>config_load</title>
<programlisting>
// load config variables and assign them
$smarty->config_load('my.conf');

// load a section
$smarty->config_load('my.conf','foobar');</programlisting>
</example>
		</sect1>
		<sect1 id="api.display">
			<title>display</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>display</function></funcdef>
				<paramdef>string <parameter>template</parameter></paramdef>
				<paramdef>string <parameter><optional>cache_id</optional></parameter></paramdef>
				<paramdef>string <parameter><optional>compile_id</optional></parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                This displays the template. Supply a valid <link
                linkend="template.resources">template resource</link>
                type and path. As an optional second parameter, you can pass a
                cache id. See the <link linkend="caching">caching
                section</link> for more information.
			</para>
			<para>
				As an optional third parameter, you can pass a compile id. This
				is in the event that you want to compile different versions of
				the same template, such as having separate templates compiled
				for different languages. Another use for compile_id is when you
				use more than one $template_dir but only one $compile_dir. Set
				a separate compile_id for each $template_dir, otherwise
				templates of the same name will overwrite each other. You can
				also set the <link
				linkend="variable.compile.id">$compile_id</link> variable once
				instead of passing this to each call to display().
			</para>
<example>
<title>display</title>
<programlisting>
include("Smarty.class.php");
$smarty = new Smarty;
$smarty->caching = true;

// only do db calls if cache doesn't exist
if(!$smarty->is_cached("index.tpl"))
{

    // dummy up some data
    $address = "245 N 50th";
    $db_data = array(
	    "City" => "Lincoln",
	    "State" => "Nebraska",
	    "Zip" = > "68502"
	    );

    $smarty->assign("Name","Fred");
    $smarty->assign("Address",$address);
    $smarty->assign($db_data);

}

// display the output
$smarty->display("index.tpl");</programlisting>
</example>
			<para>
			Use the syntax for <link
			linkend="template.resources">template resources</link> to
			display files outside of the $template_dir directory.
			</para>
<example>
<title>function display template resource examples</title>
<programlisting>
// absolute filepath
$smarty->display("/usr/local/include/templates/header.tpl");

// absolute filepath (same thing)
$smarty->display("file:/usr/local/include/templates/header.tpl");

// windows absolute filepath (MUST use "file:" prefix)
$smarty->display("file:C:/www/pub/templates/header.tpl");

// include from template resource named "db"
$smarty->display("db:header.tpl");</programlisting>
</example>

		</sect1>
		<sect1 id="api.fetch">
			<title>fetch</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>string <function>fetch</function></funcdef>
				<paramdef>string <parameter>template</parameter></paramdef>
				<paramdef>string <parameter><optional>cache_id</optional></parameter></paramdef>
				<paramdef>string <parameter><optional>compile_id</optional></parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                This returns the template output instead of displaying it.
                Supply a valid <link
                linkend="template.resources">template resource</link>
                type and path. As an optional second parameter, you can pass a
                cache id. See the <link linkend="caching">caching
                section</link> for more information.
			</para>
			<para>
				As an optional third parameter, you can pass a compile id. This
				is in the event that you want to compile different versions of
				the same template, such as having separate templates compiled
				for different languages. Another use for compile_id is when you
				use more than one $template_dir but only one $compile_dir. Set
				a separate compile_id for each $template_dir, otherwise
				templates of the same name will overwrite each other. You can
				also set the <link
				linkend="variable.compile.id">$compile_id</link> variable once
				instead of passing this to each call to fetch().
			</para>
<example>
<title>fetch</title>
<programlisting>
include("Smarty.class.php");
$smarty = new Smarty;

$smarty->caching = true;

// only do db calls if cache doesn't exist
if(!$smarty->is_cached("index.tpl"))
{

    // dummy up some data
    $address = "245 N 50th";
    $db_data = array(
	    "City" => "Lincoln",
	    "State" => "Nebraska",
	    "Zip" = > "68502"
	    );

    $smarty->assign("Name","Fred");
    $smarty->assign("Address",$address);
    $smarty->assign($db_data);

}

// capture the output
$output = $smarty->fetch("index.tpl");

// do something with $output here

echo $output;</programlisting>
</example>
		</sect1>
		<sect1 id="api.get.config.vars">
			<title>get_config_vars</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>array <function>get_config_vars</function></funcdef>
				<paramdef>string <parameter><optional>varname</optional></parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
				This returns the given loaded config variable value. If no parameter
				is given, an array of all loaded config variables is returned.
			</para>
<example>
<title>get_config_vars</title>
<programlisting>
// get loaded config template var 'foo'
$foo = $smarty->get_config_vars('foo');

// get all loaded config template vars
$config_vars = $smarty->get_config_vars();

// take a look at them
print_r($config_vars);</programlisting>
</example>
		</sect1>
		<sect1 id="api.get.registered.object">
			<title>get_registered_object</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>array <function>get_registered_object</function></funcdef>
				<paramdef>string <parameter>object_name</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
				This returns a reference to a registered object. This is useful
				from within a custom function when you need direct access to a
				registered object.
			</para>
<example>
<title>get_registered_object</title>
<programlisting>
function smarty_block_foo($params, &amp;$smarty) {
	if (isset[$params['object']]) {
		// get reference to registered object
   		$obj_ref =&amp; $smarty->&amp;get_registered_object($params['object']);
		// use $obj_ref is now a reference to the object
	}
}</programlisting>
</example>
		</sect1>
		<sect1 id="api.get.template.vars">
			<title>get_template_vars</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>array <function>get_template_vars</function></funcdef>
				<paramdef>string <parameter><optional>varname</optional></parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
				This returns the given assigned variable value. If no parameter
				is given, an array of all assigned variables is returned.
			</para>
<example>
<title>get_template_vars</title>
<programlisting>
// get assigned template var 'foo'
$foo = $smarty->get_template_vars('foo');

// get all assigned template vars
$tpl_vars = $smarty->get_template_vars();

// take a look at them
print_r($tpl_vars);</programlisting>
</example>
		</sect1>
		<sect1 id="api.is.cached">
			<title>is_cached</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>is_cached</function></funcdef>
				<paramdef>string <parameter>template</parameter></paramdef>
				<paramdef>[string <parameter>cache_id</parameter>]</paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                This returns true if there is a valid cache for this template.
                This only works if <link
                linkend="variable.caching">caching</link> is set to true.
			</para>
<example>
<title>is_cached</title>
<programlisting>
$smarty->caching = true;

if(!$smarty->is_cached("index.tpl")) {
    // do database calls, assign vars here
}

$smarty->display("index.tpl");</programlisting>
</example>
            <para>
                You can also pass a cache id as an an optional second parameter
                in case you want multiple caches for the given template.
            </para>
<example>
<title>is_cached with multiple-cache template</title>
<programlisting>
$smarty->caching = true;

if(!$smarty->is_cached("index.tpl","FrontPage")) {
    // do database calls, assign vars here
}

$smarty->display("index.tpl","FrontPage");</programlisting>
</example>
		</sect1>
        <sect1 id="api.load.filter">
         <title>load_filter</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>load_filter</function></funcdef>
           <paramdef>string <parameter>type</parameter></paramdef>
           <paramdef>string <parameter>name</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          This function can be used to load a filter plugin. The first
          argument specifies the type of the filter to load and can be one
          of the following: 'pre', 'post', or 'output'. The second argument
          specifies the name of the filter plugin, for example, 'trim'.
         </para>
<example>
<title>loading filter plugins</title>
<programlisting>
$smarty->load_filter('pre', 'trim'); // load prefilter named 'trim'
$smarty->load_filter('pre', 'datefooter'); // load another prefilter named 'datefooter'
$smarty->load_filter('output', 'compress'); // load output filter named 'compress'</programlisting>
</example>
        </sect1>
		<sect1 id="api.register.block">
			<title>register_block</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>register_block</function></funcdef>
				<paramdef>string <parameter>name</parameter></paramdef>
				<paramdef>string <parameter>impl</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
             Use this to dynamically register block functions plugins.
             Pass in the block function name, followed by the PHP
             function name that implements it.
			</para>
<example>
<title>register_block</title>
<programlisting>
/* PHP */
$smarty->register_block("translate", "do_translation");

function do_translation ($params, $content, &$smarty) {
    if ($content) {
        $lang = $params['lang'];
        // do some translation with $content
        echo $translation;
    }
}

{* template *}
{translate lang="br"}
   Hello, world!
{/translate}</programlisting>
</example>
		</sect1>
		<sect1 id="api.register.compiler.function">
			<title>register_compiler_function</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>register_compiler_function</function></funcdef>
				<paramdef>string <parameter>name</parameter></paramdef>
				<paramdef>string <parameter>impl</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                Use this to dynamically register a compiler function plugin.
                Pass in the compiler function name, followed by the PHP
                function that implements it.
			</para>
		</sect1>
		<sect1 id="api.register.function">
			<title>register_function</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>register_function</function></funcdef>
				<paramdef>string <parameter>name</parameter></paramdef>
				<paramdef>string <parameter>impl</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
             Use this to dynamically register template function plugins.
             Pass in the template function name, followed by the PHP
             function name that implements it.
			</para>
<example>
<title>register_function</title>
<programlisting>
$smarty->register_function("date_now", "print_current_date");

function print_current_date ($params) {
    extract($params);
    if(empty($format))
        $format="%b %e, %Y";
    echo strftime($format,time());
}

// now you can use this in Smarty to print the current date: {date_now}
// or, {date_now format="%Y/%m/%d"} to format it.</programlisting>
</example>
		</sect1>
		<sect1 id="api.register.modifier">
         <title>register_modifier</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>register_modifier</function></funcdef>
           <paramdef>string <parameter>name</parameter></paramdef>
           <paramdef>string <parameter>impl</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          Use this to dynamically register modifier plugin. Pass in the
          template modifier name, followed by the PHP function that it
          implements it.
         </para>
<example>
<title>register_modifier</title>
<programlisting>
// let's map PHP's stripslashes function to a Smarty modifier.

$smarty->register_modifier("sslash","stripslashes");

// now you can use {$var|sslash} to strip slashes from variables</programlisting>
</example>
		</sect1>
		<sect1 id="api.register.object">
			<title>register_object</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>register_object</function></funcdef>
				<paramdef>string <parameter>object_name</parameter></paramdef>
				<paramdef>object <parameter>$object</parameter></paramdef>
				<paramdef>array <parameter>allowed methods/properties</parameter></paramdef>
				<paramdef>boolean <parameter>format</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
            <para>
			This is to register an object for use in the templates. See the
			<link linkend="advanced.features.objects">object section</link>
			of the manual for examples.
            </para>
		</sect1>
		<sect1 id="api.register.outputfilter">
			<title>register_outputfilter</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>register_outputfilter</function></funcdef>
				<paramdef>string <parameter>function_name</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
            <para>
             Use this to dynamically register outputfilters to operate on
             a template's output before it is displayed. See
             <link linkend="advanced.features.outputfilters">template output
             filters</link>
             for more information on how to set up an output filter function.
            </para>
		</sect1>
		<sect1 id="api.register.postfilter">
			<title>register_postfilter</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>register_postfilter</function></funcdef>
				<paramdef>string <parameter>function_name</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                Use this to dynamically register postfilters to run templates
                through after they are compiled. See <link
                linkend="advanced.features.postfilters">template postfilters</link> for
                more information on how to setup a postfiltering function.
			</para>
		</sect1>
		<sect1 id="api.register.prefilter">
			<title>register_prefilter</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>register_prefilter</function></funcdef>
				<paramdef>string <parameter>function_name</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                Use this to dynamically register prefilters to run templates
                through before they are compiled. See <link
                linkend="advanced.features.prefilters">template prefilters</link> for
                more information on how to setup a prefiltering function.
			</para>
		</sect1>
        <sect1 id="api.register.resource">
         <title>register_resource</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>register_resource</function></funcdef>
           <paramdef>string <parameter>name</parameter></paramdef>
           <paramdef>array <parameter>resource_funcs</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          Use this to dynamically register a resource plugin with Smarty.
          Pass in the name of the resource and the array of PHP functions
          implementing it. See
          <link linkend="template.resources">template resources</link>
          for more information on how to setup a function for fetching
          templates.
         </para>
<example>
<title>register_resource</title>
<programlisting>
$smarty->register_resource("db", array("db_get_template",
                                       "db_get_timestamp",
                                       "db_get_secure",
                                       "db_get_trusted"));</programlisting>
</example>
		</sect1>
        <sect1 id="api.trigger.error">
         <title>trigger_error</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>trigger_error</function></funcdef>
           <paramdef>string <parameter>error_msg</parameter></paramdef>
           <paramdef>[int <parameter>level</parameter>]</paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          This function can be used to output an error message using Smarty.
          <parameter>level</parameter> parameter can be one of the values
          used for trigger_error() PHP function, i.e. E_USER_NOTICE,
          E_USER_WARNING, etc. By default it's E_USER_WARNING.
         </para>
        </sect1>

        <sect1 id="api.template.exists">
         <title>template_exists</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>bool <function>template_exists</function></funcdef>
           <paramdef>string <parameter>template</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          This function checks whether the specified template exists. It can
          accept either a path to the template on the filesystem or a
          resource string specifying the template.
         </para>
        </sect1>
        <sect1 id="api.unregister.block">
         <title>unregister_block</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>unregister_block</function></funcdef>
           <paramdef>string <parameter>name</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          Use this to dynamically unregister block function plugin.
          Pass in the block function name.
         </para>
		</sect1>
        <sect1 id="api.unregister.compiler.function">
         <title>unregister_compiler_function</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>unregister_compiler_function</function></funcdef>
           <paramdef>string <parameter>name</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          Use this to dynamically unregister a compiler function. Pass in
          the name of the compiler function.
         </para>
        </sect1>
		<sect1 id="api.unregister.function">
         <title>unregister_function</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>unregister_function</function></funcdef>
           <paramdef>string <parameter>name</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          Use this to dynamically unregister template function plugin.
          Pass in the template function name.
         </para>
<example>
<title>unregister_function</title>
<programlisting>
// we don't want template designers to have access to system files

$smarty->unregister_function("fetch");</programlisting>
</example>
		</sect1>
		<sect1 id="api.unregister.modifier">
         <title>unregister_modifier</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>unregister_modifier</function></funcdef>
           <paramdef>string <parameter>name</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          Use this to dynamically unregister modifier plugin. Pass in the
          template modifier name.
         </para>
<example>
<title>unregister_modifier</title>
<programlisting>
// we don't want template designers to strip tags from elements

$smarty->unregister_modifier("strip_tags");</programlisting>
</example>
		</sect1>
		<sect1 id="api.unregister.object">
			<title>unregister_object</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>unregister_object</function></funcdef>
				<paramdef>string <parameter>object_name</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                Use this to unregister an object.
			</para>
		</sect1>
		<sect1 id="api.unregister.outputfilter">
			<title>unregister_outputfilter</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>unregister_outputfilter</function></funcdef>
				<paramdef>string <parameter>function_name</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                Use this to dynamically unregister an output filter.
			</para>
		</sect1>
		<sect1 id="api.unregister.postfilter">
			<title>unregister_postfilter</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>unregister_postfilter</function></funcdef>
				<paramdef>string <parameter>function_name</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                Use this to dynamically unregister a postfilter.
			</para>
		</sect1>
		<sect1 id="api.unregister.prefilter">
			<title>unregister_prefilter</title>
			<funcsynopsis>
			<funcprototype>
			<funcdef>void <function>unregister_prefilter</function></funcdef>
				<paramdef>string <parameter>function_name</parameter></paramdef>
			</funcprototype>
			</funcsynopsis>
			<para>
                Use this to dynamically unregister a prefilter.
			</para>
		</sect1>
        <sect1 id="api.unregister.resource">
         <title>unregister_resource</title>
         <funcsynopsis>
          <funcprototype>
           <funcdef>void <function>unregister_resource</function></funcdef>
           <paramdef>string <parameter>name</parameter></paramdef>
          </funcprototype>
         </funcsynopsis>
         <para>
          Use this to dynamically unregister a resource plugin. Pass in the
          name of the resource.
         </para>
<example>
<title>unregister_resource</title>
<programlisting>
$smarty->unregister_resource("db");</programlisting>
</example>
		</sect1>
       </chapter>

  <chapter id="caching">
   <title>Caching</title>
   <para>
   Caching is used to speed up a call to <link
   linkend="api.display">display()</link> or <link
   linkend="api.fetch">fetch()</link> by saving its output to a file. If a
   cached version of the call is available, that is displayed instead of
   regenerating the output. Caching can speed things up tremendously,
   especially templates with longer computation times. Since the output of
   display() or fetch() is cached, one cache file could conceivably be made up
   of several template files, config files, etc.
   </para>
   <para>
   Since templates are dynamic, it is important to be careful what you are
   caching and for how long. For instance, if you are displaying the front page
   of your website that does not change its content very often, it might work
   well to cache this page for an hour or more. On the other hand, if you are
   displaying a page with a weather map containing new information by the
   minute, it would not make sense to cache this page.
   </para>
   <sect1 id="caching.setting.up">
   <title>Setting Up Caching</title>
   <para>
   The first thing to do is enable caching. This is done by setting <link
   linkend="variable.caching">$caching</link> = true (or 1.)     
   </para>
    <example>
     <title>enabling caching</title>
     <programlisting>
require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

$smarty->display('index.tpl');</programlisting>
    </example>
	<para>
	With caching enabled, the function call to display('index.tpl') will render
	the template as usual, but also saves a copy of its output to a file (a
	cached copy) in the <link linkend="variable.cache.dir">$cache_dir</link>.
	Upon the next call to display('index.tpl'), the cached copy will be used
	instead of rendering the template again.
	</para>
	<note>
	<title>Technical Note</title>
	<para>
	The files in the $cache_dir are named similar to the template name.
	Although they end in the ".php" extention, they are not really executable
	php scripts. Do not edit these files!
	</para>
	</note>
	<para>
	Each cached page has a limited lifetime determined by <link
	linkend="variable.cache.lifetime">$cache_lifetime</link>. The default value
	is 3600 seconds, or 1 hour. After that time expires, the cache is
	regenerated. It is possible to give individual caches their own expiration
	time by setting $caching = 2. See the documentation on <link
	linkend="variable.cache.lifetime">$cache_lifetime</link> for details.
	</para>
    <example>
     <title>setting cache_lifetime per cache</title>
     <programlisting>
require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = 2; // lifetime is per cache

// set the cache_lifetime for index.tpl to 15 minutes
$smarty->cache_lifetime = 300;
$smarty->display('index.tpl');

// set the cache_lifetime for home.tpl to 1 hour
$smarty->cache_lifetime = 3600;
$smarty->display('home.tpl');

// NOTE: the following $cache_lifetime setting will not work when $caching = 2.
// The cache lifetime for home.tpl has already been set
// to 1 hour, and will no longer respect the value of $cache_lifetime.
// The home.tpl cache will still expire after 1 hour.
$smarty->cache_lifetime = 30; // 30 seconds
$smarty->display('home.tpl');</programlisting>
    </example>
	<para>
	If <link linkend="variable.compile.check">$compile_check</link> is enabled,
	every template file and config file that is involved with the cache file is
	checked for modification. If any of the files have been modified since the
	cache was generated, the cache is immediately regenerated. This is a slight
	overhead so for optimum performance, leave $compile_check set to false.
	</para>
    <example>
     <title>enabling $compile_check</title>
     <programlisting>
require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;
$smarty->compile_check = true;

$smarty->display('index.tpl');</programlisting>
	</example>
	<para>
	If <link linkend="variable.force.compile">$force_compile</link> is enabled,
	the cache files will always be regenerated. This effectively turns off
	caching. $force_compile is usually for debugging purposes only, a more
	efficient way of disabling caching is to set <link
	linkend="variable.caching">$caching</link> = false (or 0.)
	</para>
	<para>
	The <link linkend="api.is.cached">is_cached()</link> function
	can be used to test if a template has a valid cache or not. If you have a
	cached template that requires something like a database fetch, you can use
	this to skip that process.
	</para>
    <example>
     <title>using is_cached()</title>
     <programlisting>
require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

if(!$smarty->is_cached('index.tpl')) {
	// No cache available, do variable assignments here.
	$contents = get_database_contents();
	$smarty->assign($contents);
}

$smarty->display('index.tpl');</programlisting>
    </example>
	<para>
	You can keep parts of a page dynamic with the <link
	linkend="language.function.insert">insert</link> template function. Let's
	say the whole page can be cached except for a banner that is displayed down
	the right side of the page. By using an insert function for the banner, you
	can keep this element dynamic within the cached content. See the
	documentation on <link linkend="language.function.insert">insert</link> for
	details and examples.
	</para>
	<para>
	You can clear all the cache files with the <link
	linkend="api.clear.all.cache">clear_all_cache()</link> function, or
	individual cache files (or groups) with the <link
	linkend="api.clear.cache">clear_cache()</link> function.	
	</para>
    <example>
     <title>clearing the cache</title>
     <programlisting>
require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

// clear out all cache files
$smarty->clear_all_cache();

// clear only cache for index.tpl
$smarty->clear_cache('index.tpl');

$smarty->display('index.tpl');</programlisting>
    </example>
   </sect1>
   <sect1 id="caching.multiple.caches">
    <title>Multiple Caches Per Page</title>
	<para>
	You can have multiple cache files for a single call to display() or
	fetch(). Let's say that a call to display('index.tpl') may have several
	different output contents depending on some condition, and you want
	separate caches for each one. You can do this by passing a cache_id as the
	second parameter to the function call.
	</para>
    <example>
     <title>passing a cache_id to display()</title>
     <programlisting>
require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

$my_cache_id = $_GET['article_id'];

$smarty->display('index.tpl',$my_cache_id);</programlisting>
    </example>
	<para>
	Above, we are passing the variable $my_cache_id to display() as the
	cache_id. For each unique value of $my_cache_id, a separate cache will be
	generated for index.tpl. In this example, "article_id" was passed in the
	URL and is used as the cache_id.
	</para>
	<note>
	<title>Technical Note</title>
	<para>
	Be very cautious when passing values from a client (web browser) into
	Smarty (or any PHP application.) Although the above example of using the
	article_id from the URL looks handy, it could have bad consequences. The
	cache_id is used to create a directory on the file system, so if the user
	decided to pass an extremely large value for article_id, or write a script
	that sends random article_ids at a rapid pace, this could possibly cause
	problems at the server level. Be sure to sanitize any data passed in before
	using it. In this instance, maybe you know the article_id has a length of
	10 characters and is made up of alpha-numerics only, and must be a valid
	article_id in the database. Check for this!
	</para>
	</note>
	<para>
	Be sure to pass the same cache_id as the
	second parameter to <link linkend="api.is.cached">is_cached()</link> and
	<link linkend="api.clear.cache">clear_cache()</link>.
	</para>
	<example>
     <title>passing a cache_id to is_cached()</title>
     <programlisting>
require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

$my_cache_id = $_GET['article_id'];

if(!$smarty->is_cached('index.tpl',$my_cache_id)) {
	// No cache available, do variable assignments here.
	$contents = get_database_contents();
	$smarty->assign($contents);
}

$smarty->display('index.tpl',$my_cache_id);</programlisting>
    </example>
	<para>
	You can clear all caches for a particular cache_id by passing null as the
	first parameter to clear_cache().
	</para>
	<example>
     <title>clearing all caches for a particular cache_id</title>
     <programlisting>
require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

// clear all caches with "sports" as the cache_id
$smarty->clear_cache(null,"sports");

$smarty->display('index.tpl',"sports");</programlisting>
    </example>
	<para>
	In this manner, you can "group" your caches together by giving them the
	same cache_id.
	</para>
   </sect1>
   <sect1 id="caching.groups">
    <title>Cache Groups</title>
	<para>
	You can do more elaborate grouping by setting up cache_id groups. This is
	accomplished by separating each sub-group with a vertical bar "|" in the
	cache_id value. You can have as many sub-groups as you like.
	</para>
	<example>
     <title>cache_id groups</title>
     <programlisting>
require('Smarty.class.php');
$smarty = new Smarty;

$smarty->caching = true;

// clear all caches with "sports|basketball" as the first two cache_id groups
$smarty->clear_cache(null,"sports|basketball");

// clear all caches with "sports" as the first cache_id group. This would
// include "sports|basketball", or "sports|(anything)|(anything)|(anything)|..."
$smarty->clear_cache(null,"sports");

$smarty->display('index.tpl',"sports|basketball");</programlisting>
    </example>
   <note>
   <title>Technical Note</title>
   <para>
   The cache grouping does NOT use the path to the template as any part of the
   cache_id. For example, if you have display('themes/blue/index.tpl'), you
   cannot clear the cache for everything under the "themes/blue" directory. If
   you want to do that, you must group them in the cache_id, such as
   display('themes/blue/index.tpl','themes|blue'); Then you can clear the
   caches for the blue theme with clear_cache(null,'themes|blue');
   </para>
   </note>
   </sect1>
  </chapter>

  <chapter id="advanced.features">
   <title>Advanced Features</title>
   <sect1 id="advanced.features.objects">
    <title>Objects</title>
    <para>
     Smarty allows access to PHP objects through the templates. There are
	 two ways to access them. One way is to register objects to the template,
	 then use access them via syntax similar to custom functions. The other way
	 is to assign objects to the templates and access them much like any other
	 assigned variable. The first method has a much nicer template syntax. It
	 is also more secure, as a registered object can be restricted to certain
	 methods or properties. However, a registered object cannot be looped over
	 or assigned in arrays of objects, etc. The method you choose will be
	 determined by your needs, but use the first method whenever possible to
	 keep template syntax to a minimum.
    </para>
	<para>
    If security is enabled, no private methods or functions can be accessed
	(begininning with "_"). If a method and property of the same name exist,
	the method will be used.
	</para>
	<para>
	You can restrict the methods and properties that can be accessed by
	listing them in an array as the third registration parameter.
	</para>
	<para>
	By default, parameters passed to objects through the templates are passed
	the same way custom functions get them. An associative array is passed
	as the first parameter, and the smarty object as the second. If you want
	the parameters passed one at a time for each argument like traditional
	object parameter passing, set the fourth registration parameter to false.
	</para>
    <example>
     <title>using a registered or assigned object</title>
     <programlisting>
&lt;?php
// the object

class My_Object() {
	function meth1($params, &$smarty_obj) {
		return "this is my meth1";
	}
}

$myobj = new My_Object;
// registering the object (will be by reference)
$smarty->register_object("foobar",$myobj);
// if we want to restrict access to certain methods or properties, list them
$smarty->register_object("foobar",$myobj,array('meth1','meth2','prop1'));
// if you want to use the traditional object parameter format, pass a boolean of false
$smarty->register_object("foobar",$myobj,null,false);

// We can also assign objects. Assign by ref when possible.
$smarty->assign_by_ref("myobj", $myobj);

$smarty->display("index.tpl");
?&gt;

TEMPLATE:

{* access our registered object *}
{foobar->meth1 p1="foo" p2=$bar}

{* you can also assign the output *}
{foobar->meth1 p1="foo" p2=$bar assign="output"}
the output was {$output)

{* access our assigned object *}
{$myobj->meth1("foo",$bar)}</programlisting>
    </example>
  </sect1>
   <sect1 id="advanced.features.prefilters">
    <title>Prefilters</title>
    <para>
     Template prefilters are PHP functions that your templates are ran through
     before they are compiled. This is good for preprocessing your templates
     to remove unwanted comments, keeping an eye on what people are putting
     in their templates, etc. Prefilters can be either
     <link linkend="api.register.prefilter">registered</link> or loaded from
     the plugins directory by using
     <link linkend="api.load.filter">load_filter()</link> function or by
     setting
     <link linkend="variable.autoload.filters">$autoload_filters</link> variable.
     Smarty will pass the template source code as the first argument, and
     expect the function to return the resulting template source code.
    </para>
    <example>
     <title>using a template prefilter</title>
     <programlisting>
&lt;?php
// put this in your application
function remove_dw_comments($tpl_source, &$smarty)
{
    return preg_replace("/&lt;!--#.*--&gt;/U","",$tpl_source);
}

// register the prefilter
$smarty->register_prefilter("remove_dw_comments");
$smarty->display("index.tpl");
?&gt;

{* Smarty template index.tpl *}
&lt;!--# this line will get removed by the prefilter --&gt;</programlisting>
    </example>
   </sect1>

   <sect1 id="advanced.features.postfilters">
    <title>Postfilters</title>
    <para>
     Template postfilters are PHP functions that your templates are ran through
     after they are compiled. Postfilters can be either 
     <link linkend="api.register.postfilter">registered</link> or loaded
     from the plugins directory by using
     <link linkend="api.load.filter">load_filter()</link> function or by
     setting
     <link linkend="variable.autoload.filters">$autoload_filters</link>
     variable. Smarty will pass the compiled template code as the first
     argument, and expect the function to return the result of the
     processing.
    </para>
    <example>
     <title>using a template postfilter</title>
     <programlisting>
&lt;?php
// put this in your application
function add_header_comment($tpl_source, &$smarty)
{
    return "&lt;?php echo \"&lt;!-- Created by Smarty! --&gt;\n\" ?&gt;\n".$tpl_source;
}

// register the postfilter
$smarty->register_postfilter("add_header_comment");
$smarty->display("index.tpl");
?&gt;

{* compiled Smarty template index.tpl *}
&lt;!-- Created by Smarty! --&gt;
{* rest of template content... *}</programlisting>
    </example>
  </sect1>

  <sect1 id="advanced.features.outputfilters">
   <title>Output Filters</title>
   <para>
    When the template is invoked via display() or fetch(), its output can be
    sent through one or more output filters. This differs from postfilters
    because postfilters operate on compiled templates before they are saved to
    the disk, and output filters operate on the template output when it is
    executed.
   </para>

   <para>
    Output filters can be either 
    <link linkend="api.register.outputfilter">registered</link> or loaded
    from the plugins directory by using
    <link linkend="api.load.filter">load_filter()</link> function or by
    setting
    <link linkend="variable.autoload.filters">$autoload_filters</link>
    variable. Smarty will pass the template output as the first argument,
    and expect the function to return the result of the processing.
   </para>
   <example>
    <title>using a template outputfilter</title>
    <programlisting>
&lt;?php
// put this in your application
function protect_email($tpl_output, &$smarty)
{
    $tpl_output =
       preg_replace('!(\S+)@([a-zA-Z0-9\.\-]+\.([a-zA-Z]{2,3}|[0-9]{1,3}))!',
                    '$1%40$2', $tpl_output);
    return $tpl_output;
}

// register the outputfilter
$smarty->register_outputfilter("protect_email");
$smarty->display("index.tpl");

// now any occurrence of an email address in the template output will have
// a simple protection against spambots
?&gt;</programlisting>
   </example>
  </sect1>

  <sect1 id="section.template.cache.handler.func">
   <title>Cache Handler Function</title>
   <para>
    As an alternative to using the default file-based caching mechanism, you
    can specify a custom cache handling function that will be used to read,
    write and clear cached files.
   </para>
   <para>
    Create a function in your application that Smarty will use as a
    cache handler. Set the name of it in the
    <link linkend="variable.cache.handler.func">$cache_handler_func</link>
    class variable. Smarty will now use this to handle cached data. The
    first argument is the action, which will be one of 'read', 'write' and
    'clear'. The second parameter is the Smarty object. The third parameter
    is the cached content. Upon a write, Smarty passes the cached content
    in these parameters. Upon a 'read', Smarty expects your function to
    accept this parameter by reference and populate it with the cached
    data. Upon a 'clear', pass a dummy variable here since it is not used.
    The fourth parameter is the name of the template file (needed for
    read/write), the fifth parameter is the cache_id (optional), and the
    sixth is the compile_id (optional).
   </para>
   <example>
    <title>example using MySQL as a cache source</title>
    <programlisting>
&lt;?php
/*

example usage:

include('Smarty.class.php');
include('mysql_cache_handler.php');

$smarty = new Smarty;
$smarty-&gt;cache_handler_func = 'mysql_cache_handler';

$smarty-&gt;display('index.tpl');


mysql database is expected in this format:
	
create database SMARTY_CACHE;

create table CACHE_PAGES(
CacheID char(32) PRIMARY KEY,
CacheContents MEDIUMTEXT NOT NULL
);

*/

function mysql_cache_handler($action, &$smarty_obj, &$cache_content, $tpl_file=null, $cache_id=null, $compile_id=null)
{
	// set db host, user and pass here
	$db_host = 'localhost';
	$db_user = 'myuser';
	$db_pass = 'mypass';
	$db_name = 'SMARTY_CACHE';
	$use_gzip = false;
	
	// create unique cache id
	$CacheID = md5($tpl_file.$cache_id.$compile_id);
	
	if(! $link = mysql_pconnect($db_host, $db_user, $db_pass)) {
		$smarty_obj-&gt;_trigger_error_msg("cache_handler: could not connect to database");
		return false;
	}
	mysql_select_db($db_name);

	switch ($action) {
		case 'read':
			// save cache to database
			$results = mysql_query("select CacheContents from CACHE_PAGES where CacheID='$CacheID'");
			if(!$results) {
				$smarty_obj-&gt;_trigger_error_msg("cache_handler: query failed.");			
			}
			$row = mysql_fetch_array($results,MYSQL_ASSOC);
			
			if($use_gzip && function_exists("gzuncompress")) {
				$cache_contents = gzuncompress($row["CacheContents"]);
			} else {
				$cache_contents = $row["CacheContents"];
			}
			$return = $results;
			break;
		case 'write':
			// save cache to database
			
			if($use_gzip && function_exists("gzcompress")) {
				// compress the contents for storage efficiency
				$contents = gzcompress($cache_content);
			} else {
				$contents = $cache_content;
			}
			$results = mysql_query("replace into CACHE_PAGES values(
							'$CacheID',
							'".addslashes($contents)."')
						");
			if(!$results) {
				$smarty_obj-&gt;_trigger_error_msg("cache_handler: query failed.");			
			}
			$return = $results;
			break;
		case 'clear':
			// clear cache info
			if(empty($cache_id) && empty($compile_id) && empty($tpl_file)) {
				// clear them all
				$results = mysql_query("delete from CACHE_PAGES");			
			} else {
				$results = mysql_query("delete from CACHE_PAGES where CacheID='$CacheID'");			
			}
			if(!$results) {
				$smarty_obj-&gt;_trigger_error_msg("cache_handler: query failed.");			
			}
			$return = $results;
			break;
		default:
			// error, unknown action
			$smarty_obj-&gt;_trigger_error_msg("cache_handler: unknown action \"$action\"");
			$return = false;
			break;
	}
	mysql_close($link);
	return $return;
	
}

?&gt;</programlisting>
    </example>
  </sect1>

  <sect1 id="template.resources">
   <title>Resources</title>
   <para>
    The templates may come from a variety of sources. When you display or
    fetch a template, or when you include a template from within another
    template, you supply a resource type, followed by the appropriate path
    and template name.
   </para>
   <sect2 id="templates.from.template.dir">
    <title>Templates from $template_dir</title>
    <para>
     Templates from the $template_dir do not require a template
     resource, although you can use the file: resource for consistancy.
     Just supply the path to the template you want to use relative to
     the $template_dir root directory.
    </para>
    <example>
     <title>using templates from $template_dir</title>
     <programlisting>
// from PHP script
$smarty->display("index.tpl");
$smarty->display("admin/menu.tpl");
$smarty->display("file:admin/menu.tpl"); // same as one above

{* from within Smarty template *}
{include file="index.tpl"}
{include file="file:index.tpl"} {* same as one above *}</programlisting>
    </example>
   </sect2>
   <sect2 id="templates.from.any.dir">
    <title>Templates from any directory</title>
    <para>
     Templates outside of the $template_dir require the file: template
     resource type, followed by the absolute path and name of the
     template.
    </para>
    <example>
     <title>using templates from any directory</title>
     <programlisting>
// from PHP script
$smarty->display("file:/export/templates/index.tpl");
$smarty->display("file:/path/to/my/templates/menu.tpl");

{* from within Smarty template *}
{include file="file:/usr/local/share/templates/navigation.tpl"}</programlisting>
    </example>

    <sect3>
     <title>Windows Filepaths</title>
     <para>
      If you are using a Windows machine, filepaths usually include a
      drive letter (C:) at the beginning of the pathname. Be sure to use
      "file:" in the path to avoid namespace conflicts and get the
      desired results.
     </para>
     <example>
      <title>using templates from windows file paths</title>
      <programlisting>
// from PHP script
$smarty->display("file:C:/export/templates/index.tpl");
$smarty->display("file:F:/path/to/my/templates/menu.tpl");

{* from within Smarty template *}
{include file="file:D:/usr/local/share/templates/navigation.tpl"}</programlisting>
     </example>
    </sect3>
   </sect2>

   <sect2 id="templates.from.elsewhere">
    <title>Templates from other sources</title>
    <para>
     You can retrieve templates using whatever possible source you can
     access with PHP: databases, sockets, LDAP, and so on. You do this
     by writing resource plugin functions and registering them with
     Smarty.
    </para>

    <para>
     See <link linkend="plugins.resources">resource plugins</link>
     section for more information on the functions you are supposed
     to provide.
    </para>

    <note>
     <para>
      Note that you cannot override the built-in
      <literal>file</literal> resource, but you can provide a resource
      that fetches templates from the file system in some other way by
      registering under another resource name.
     </para>
    </note>
    <example>
     <title>using custom resources</title>
     <programlisting>
// from PHP script

// put these function somewhere in your application
function db_get_template ($tpl_name, &amp;$tpl_source, &amp;$smarty_obj)
{
    // do database call here to fetch your template,
    // populating $tpl_source
    $sql = new SQL;
    $sql->query("select tpl_source
                   from my_table
                  where tpl_name='$tpl_name'");
    if ($sql->num_rows) {
        $tpl_source = $sql->record['tpl_source'];
        return true;
    } else {
        return false;
    }
}

function db_get_timestamp($tpl_name, &amp;$tpl_timestamp, &amp;$smarty_obj)
{
    // do database call here to populate $tpl_timestamp.
    $sql = new SQL;
    $sql->query("select tpl_timestamp
                   from my_table
                  where tpl_name='$tpl_name'");
    if ($sql->num_rows) {
        $tpl_timestamp = $sql->record['tpl_timestamp'];
        return true;
    } else {
        return false;
    }
}

function db_get_secure($tpl_name, &$smarty_obj)
{
    // assume all templates are secure
    return true;
}

function db_get_trusted($tpl_name, &$smarty_obj)
{
    // not used for templates
}

// register the resource name "db"
$smarty->register_resource("db", array("db_get_template",
                                       "db_get_timestamp",
                                       "db_get_secure",
                                       "db_get_trusted"));

// using resource from php script
$smarty->display("db:index.tpl");

{* using resource from within Smarty template *}
{include file="db:/extras/navigation.tpl"}</programlisting>
    </example>
   </sect2>

   <sect2 id="default.template.handler.function">
    <title>Default template handler function</title>
    <para>
     You can specify a function that is used to retrieve template
     contents in the event the template cannot be retrieved from its
     resource. One use of this is to create templates that do not exist
     on-the-fly.
    </para>
    <example>
     <title>using the default template handler function</title>
     <programlisting>
&lt;?php
// put this function somewhere in your application

function make_template ($resource_type, $resource_name, &amp;$template_source, &amp;$template_timestamp, &amp;$smarty_obj)
{
	if( $resource_type == 'file' ) {
		if ( ! is_readable ( $resource_name )) {
			// create the template file, return contents.
			$template_source = "This is a new template.";
			$template_timestamp = time();
			$smarty_obj->_write_file($resource_name,$template_source);
			return true;
		}
    } else {
		// not a file
		return false;
    }
}

// set the default handler
$smarty->default_template_handler_func = 'make_template';
?&gt;</programlisting>
    </example>
   </sect2>
  </sect1>
 </chapter>

 <chapter id="plugins">
  <title>Extending Smarty With Plugins</title>
  <para>
   Version 2.0 introduced the plugin architecture that is used
   for almost all the customizable functionality of Smarty. This includes:
   <itemizedlist spacing=compact>
    <listitem><simpara>functions</simpara></listitem>
    <listitem><simpara>modifiers</simpara></listitem>
    <listitem><simpara>block functions</simpara></listitem>
    <listitem><simpara>compiler functions</simpara></listitem>
    <listitem><simpara>prefilters</simpara></listitem>
    <listitem><simpara>postfilters</simpara></listitem>
    <listitem><simpara>outputfilters</simpara></listitem>
    <listitem><simpara>resources</simpara></listitem>
    <listitem><simpara>inserts</simpara></listitem>
   </itemizedlist>
   With the exception of resources, backwards compatibility with the old
   way of registering handler functions via register_* API is preserved. If
   you did not use the API but instead modified the class variables
   <literal>$custom_funcs</literal>, <literal>$custom_mods</literal>, and
   other ones directly, then you will need to adjust your scripts to either
   use the API or convert your custom functionality into plugins.
  </para>
   
  <sect1>
   <title>How Plugins Work</title>
   <para>
    Plugins are always loaded on demand. Only the specific modifiers,
    functions, resources, etc invoked in the templates scripts will be
    loaded. Moreover, each plugin is loaded only once, even if you have
    several different instances of Smarty running within the same request.
   </para>
   <para>
    Pre/postfilters and output filters are a bit of a special case. Since
    they are not mentioned in the templates, they must be registered or
    loaded explicitly via API functions before the template is processed.
    The order in which multiple filters of the same type are executed
    depends on the order in which they are registered or loaded.
   </para>
   <para>
    There is only one plugins directory (for performance reasons). To
    install a plugin, simply place it in the directory and Smarty will use
    it automatically.
   </para>
  </sect1>

   <sect1 id="plugins.naming.conventions">
    <title>Naming Conventions</title>
    <para>
     Plugin files and functions must follow a very specific naming
     convention in order to be located by Smarty.
    </para>
    <para>
     The plugin files must be named as follows:
     <blockquote>
      <para>
       <filename>
        <replaceable>type</replaceable>.<replaceable>name</replaceable>.php
       </filename>
      </para>
     </blockquote>
    </para>
    <para>
     Where <literal>type</literal> is one of these plugin types:
     <itemizedlist spacing=compact>
      <listitem><simpara>function</simpara></listitem>
      <listitem><simpara>modifier</simpara></listitem>
      <listitem><simpara>block</simpara></listitem>
      <listitem><simpara>compiler</simpara></listitem>
      <listitem><simpara>prefilter</simpara></listitem>
      <listitem><simpara>postfilter</simpara></listitem>
      <listitem><simpara>outputfilter</simpara></listitem>
      <listitem><simpara>resource</simpara></listitem>
      <listitem><simpara>insert</simpara></listitem>
     </itemizedlist>
    </para>
    <para>
     And <literal>name</literal> should be a valid identifier (letters,
     numbers, and underscores only).
    </para>
    <para>
     Some examples: <literal>function.html_select_date.php</literal>,
     <literal>resource.db.php</literal>,
     <literal>modifier.spacify.php</literal>.
    </para>
    <para>
     The plugin functions inside the plugin files must be named as follows:
     <blockquote>
      <para>
       <function>smarty_<replaceable>type</replaceable>_<replaceable>name</replaceable></function>
      </para>
     </blockquote>
    </para>
    <para>
     The meanings of <literal>type</literal> and <literal>name</literal> are
     the same as before.
    </para>
    <para>
     Smarty will output appropriate error messages if the plugin file it
     needs is not found, or if the file or the plugin function are named
     improperly.
    </para>
   </sect1>

   <sect1 id="plugins.writing">
    <title>Writing Plugins</title>
    <para>
     Plugins can be either loaded by Smarty automatically from the
     filesystem or they can be registered at runtime via one of the
     register_* API functions. They can also be unregistered by using
     unregister_* API functions.
    </para>
    <para>
     For the plugins that are registered at runtime, the name of the plugin
     function(s) does not have to follow the naming convention.
    </para>
    <para>
     If a plugin depends on some functionality provided by another plugin
     (as is the case with some plugins bundled with Smarty), then the proper
     way to load the needed plugin is this:
    </para>
    <programlisting>
require_once SMARTY_DIR . 'plugins/function.html_options.php';</programlisting>
    <para>
     As a general rule, Smarty object is always passed to the plugins as the last
     parameter (except for modifiers).
    </para>
   </sect1>

   <sect1 id="plugins.functions"><title>Template Functions</title>
    <funcsynopsis>
     <funcprototype>
      <funcdef>void <function>smarty_function_<replaceable>name</replaceable></function></funcdef>
      <paramdef>array <parameter>$params</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
    </funcsynopsis>
    <para>
     All attributes passed to template functions from the template are
     contained in the <parameter>$params</parameter> as an associative
     array. Either access those values directly, e.g.
     <varname>$params['start']</varname> or use
     <varname>extract($params)</varname> to import them into the symbol
     table.
    </para>
    <para>
	 The output (return value) of the function will be substituted in place of the
     function tag in the template (<function>fetch</function> function, for
     example). Alternatively, the function can simply perform some other
     task without any output (<function>assign</function> function).
    </para>
    <para>
     If the function needs to assign some variables to the template or use
     some other Smarty-provided functionality, it can use the supplied
     <parameter>$smarty</parameter> object to do so.
    </para>
    <para>
     See also:
     <link linkend="api.register.function">register_function()</link>,
     <link linkend="api.unregister.function">unregister_function()</link>.
    </para>
    <para>
     <example>
      <title>function plugin with output</title>
      <programlisting>
&lt;?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     function.eightball.php
 * Type:     function
 * Name:     eightball
 * Purpose:  outputs a random magic answer
 * -------------------------------------------------------------
 */
function smarty_function_eightball($params, &amp;$smarty)
{
    $answers = array('Yes',
                     'No',
                     'No way',
                     'Outlook not so good',
                     'Ask again soon',
                     'Maybe in your reality');

    $result = array_rand($answers);
    return $answers[$result];
}
?&gt;</programlisting>
     </example>
    </para>
    <para>
     which can be used in the template as:
    </para>
    <programlisting>
Question: Will we ever have time travel?
Answer: {eightball}.</programlisting>
    <para>
     <example>
      <title>function plugin without output</title>
      <programlisting>
&lt;?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     function.assign.php
 * Type:     function
 * Name:     assign
 * Purpose:  assign a value to a template variable
 * -------------------------------------------------------------
 */
function smarty_function_assign($params, &amp;$smarty)
{
    extract($params);

    if (empty($var)) {
        $smarty->trigger_error("assign: missing 'var' parameter");
        return;
    }

    if (!in_array('value', array_keys($params))) {
        $smarty->trigger_error("assign: missing 'value' parameter");
        return;
    }

    $smarty->assign($var, $value);
}
?&gt;</programlisting>
     </example>
    </para>
   </sect1>

   <sect1 id="plugins.modifiers"><title>Modifiers</title>
    <para>
     Modifiers are little functions that are applied to a variable in the
     template before it is displayed or used in some other context.
     Modifiers can be chained together.
    </para>
    <funcsynopsis>
     <funcprototype>
      <funcdef>mixed <function>smarty_modifier_<replaceable>name</replaceable></function></funcdef>
      <paramdef>mixed <parameter>$value</parameter></paramdef>
      <paramdef>[mixed <parameter>$param1</parameter>, ...]</paramdef>
     </funcprototype>
    </funcsynopsis>
    <para>
     The first parameter to the modifier plugin is the value on which
     the modifier is supposed to operate. The rest of the parameters can be
     optional, depending on what kind of operation is supposed to be
     performed.
    </para>
    <para>
     The modifier has to return the result of its processing.
    </para>
    <para>
     See also
     <link linkend="api.register.modifier">register_modifier()</link>,
     <link linkend="api.unregister.modifier">unregister_modifier()</link>.
    </para>
    <example>
     <title>simple modifier plugin</title>
     <para>
      This plugin basically aliases one of the built-in PHP functions. It
      does not have any additional parameters.
     </para>
     <programlisting>
&lt;?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     modifier.capitalize.php
 * Type:     modifier
 * Name:     capitalize
 * Purpose:  capitalize words in the string
 * -------------------------------------------------------------
 */
function smarty_modifier_capitalize($string)
{
    return ucwords($string);
}
?&gt;</programlisting>
    </example>
    <para></para>
    <example>
     <title>more complex modifier plugin</title>
     <programlisting>
&lt;?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     modifier.truncate.php
 * Type:     modifier
 * Name:     truncate
 * Purpose:  Truncate a string to a certain length if necessary,
 *           optionally splitting in the middle of a word, and 
 *           appending the $etc string.
 * -------------------------------------------------------------
 */
function smarty_modifier_truncate($string, $length = 80, $etc = '...',
                                  $break_words = false)
{
    if ($length == 0)
        return '';

    if (strlen($string) > $length) {
        $length -= strlen($etc);
        $fragment = substr($string, 0, $length+1);
        if ($break_words)
            $fragment = substr($fragment, 0, -1);
        else
            $fragment = preg_replace('/\s+(\S+)?$/', '', $fragment);
        return $fragment.$etc;
    } else
        return $string;
}
?&gt;</programlisting>
    </example>
   </sect1>

   <sect1 id="plugins.block.functions"><title>Block Functions</title>
    <funcsynopsis>
     <funcprototype>
      <funcdef>void <function>smarty_block_<replaceable>name</replaceable></function></funcdef>
      <paramdef>array <parameter>$params</parameter></paramdef>
      <paramdef>mixed <parameter>$content</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
    </funcsynopsis>
    <para>
     Block functions are functions of the form: {func} .. {/func}. In other
     words, they enclose a template block and operate on the contents of
     this block. Block functions take precedence over custom functions of
     the same name, that is, you cannot have both custom function {func} and
     block function {func} .. {/func}.
    </para>
    <para>
     Your function implementation is called twice by Smarty:
     once for the opening tag, and once for the closing tag.
    </para>
    <para>
     Only the opening tag of the block function may have attributes. All
     attributes passed to template functions from the template are contained
     in the <parameter>$params</parameter> as an associative array. You can
     either access those values directly, e.g.
     <varname>$params['start']</varname> or use
     <varname>extract($params)</varname> to import them into the symbol
     table. The opening tag attributes are also accessible to your function
     when processing the closing tag.
    </para>
    <para>
     The value of <parameter>$content</parameter> variable depends on
     whether your function is called for the opening or closing tag. In case
     of the opening tag, it will be <literal>null</literal>, and in case of
     the closing tag it will be the contents of the template block.
     Note that the template block will have already been processed by
     Smarty, so all you will receive is the template output, not the
     template source.
    </para>
    <para>
     If you have nested block functions, it's possible to find out what the
     parent block function is by accessing
     <varname>$smarty->_tag_stack</varname> variable. Just do a var_dump()
     on it and the structure should be apparent.
    </para>
    <para>
     See also:
     <link linkend="api.register.block">register_block()</link>,
     <link linkend="api.unregister.block">unregister_block()</link>.
    </para>
    <example>
     <title>block function</title>
     <programlisting>
&lt;?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     block.translate.php
 * Type:     block
 * Name:     translate
 * Purpose:  translate a block of text
 * -------------------------------------------------------------
 */
function smarty_block_translate($params, $content, &amp;$smarty)
{
    if ($content) {
        $lang = $params['lang'];
        // do some intelligent translation thing here with $content
        echo $translation;
    }
}</programlisting>
    </example>
   </sect1>

   <sect1 id="plugins.compiler.functions"><title>Compiler Functions</title>
    <para>
     Compiler functions are called only during compilation of the template.
     They are useful for injecting PHP code or time-sensitive static
     content into the template. If there is both a compiler function and a
     custom function registered under the same name, the compiler function
     has precedence.
    </para>
    <funcsynopsis>
     <funcprototype>
      <funcdef>mixed <function>smarty_compiler_<replaceable>name</replaceable></function></funcdef>
      <paramdef>string <parameter>$tag_arg</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
    </funcsynopsis>
    <para>
     The compiler function is passed two parameters: the tag argument
     string - basically, everything from the function name until the ending
     delimiter, and the Smarty object. It's supposed to return the PHP code
     to be injected into the compiled template.
    </para>
    <para>
     See also
     <link linkend="api.register.compiler.function">register_compiler_function()</link>,
     <link linkend="api.unregister.compiler.function">unregister_compiler_function()</link>.
    </para>
    <example>
     <title>simple compiler function</title>
     <programlisting>
&lt;?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     compiler.tplheader.php
 * Type:     compiler
 * Name:     tplheader
 * Purpose:  Output header containing the source file name and
 *           the time it was compiled.
 * -------------------------------------------------------------
 */
function smarty_compiler_tplheader($tag_arg, &$smarty)
{
    return "\necho '" . $smarty-&gt;_current_file . " compiled at " . date('Y-m-d H:M'). "';";
}
?&gt;</programlisting>
     <para>
      This function can be called from the template as:
     </para>
     <programlisting>
{* this function gets executed at compile time only *}
{tplheader}</programlisting>
     <para>
      The resulting PHP code in the compiled template would be something like this:
     </para>
     <programlisting>
&lt;php
echo 'index.tpl compiled at 2002-02-20 20:02';
?&gt;</programlisting>
    </example>
   </sect1>

   <sect1 id="plugins.prefilters.postfilters">
    <title>Prefilters/Postfilters</title>
    <para>
     Prefilter and postfilter plugins are very similar in concept; where
     they differ is in the execution -- more precisely the time of their
     execution.
    </para>
    <funcsynopsis>
     <funcprototype>
      <funcdef>string <function>smarty_prefilter_<replaceable>name</replaceable></function></funcdef>
      <paramdef>string <parameter>$source</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
    </funcsynopsis>
    <para>
     Prefilters are used to process the source of the template immediately
     before compilation. The first parameter to the prefilter function is
     the template source, possibly modified by some other prefilters. The
     plugin is supposed to return the modified source.  Note that this
     source is not saved anywhere, it is only used for compilation.
    </para>
    <funcsynopsis>
     <funcprototype>
      <funcdef>string <function>smarty_postfilter_<replaceable>name</replaceable></function></funcdef>
      <paramdef>string <parameter>$compiled</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
    </funcsynopsis>
    <para>
     Postfilters are used to process the compiled output of the template
     (the PHP code) immediately after the compilation is done but before the
     compiled template is saved to the filesystem. The first parameter to
     the postfilter function is the compiled template code, possibly
     modified by other postfilters. The plugin is supposed to return the
     modified version of this code.
    </para>
    <example>
     <title>prefilter plugin</title>
     <programlisting>
&lt;?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     prefilter.pre01.php
 * Type:     prefilter
 * Name:     pre01
 * Purpose:  Convert html tags to be lowercase.
 * -------------------------------------------------------------
 */
 function smarty_prefilter_pre01($source, &$smarty)
 {
     return preg_replace('!&lt;(\w+)[^&gt;]+&gt;!e', 'strtolower("$1")', $source);
 }
?&gt;</programlisting>
    </example>
    <para></para>
    <example>
     <title>postfilter plugin</title>
     <programlisting>
&lt;?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     postfilter.post01.php
 * Type:     postfilter
 * Name:     post01
 * Purpose:  Output code that lists all current template vars.
 * -------------------------------------------------------------
 */
 function smarty_postfilter_post01($compiled, &$smarty)
 {
     $compiled = "&lt;pre&gt;\n&lt;?php print_r(\$this-&gt;get_template_vars()); ?&gt;\n&lt;/pre&gt;" . $compiled;
     return $compiled;
 }
?&gt;</programlisting>
    </example>
   </sect1>

   <sect1 id="plugins.outputfilters"><title>Output Filters</title>
    <para>
     Output filter plugins operate on a template's output, after the
     template is loaded and executed, but before the output is displayed.
    </para>
    <funcsynopsis>
     <funcprototype>
      <funcdef>string <function>smarty_outputfilter_<replaceable>name</replaceable></function></funcdef>
      <paramdef>string <parameter>$template_output</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
    </funcsynopsis>
    <para>
     The first parameter to the output filter function is the template
     output that needs to be processed, and the second parameter is the
     instance of Smarty invoking the plugin. The plugin is supposed to do
     the processing and return the results.
    </para>
    <example>
     <title>output filter plugin</title>
     <programlisting>
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * File:     outputfilter.protect_email.php
 * Type:     outputfilter
 * Name:     protect_email
 * Purpose:  Converts @ sign in email addresses to %40 as 
 *           a simple protection against spambots
 * -------------------------------------------------------------
 */
 function smarty_outputfilter_protect_email($output, &$smarty)
 {
     return preg_replace('!(\S+)@([a-zA-Z0-9\.\-]+\.([a-zA-Z]{2,3}|[0-9]{1,3}))!',
                         '$1%40$2', $output);
 }
     </programlisting>
    </example>
   </sect1>

   <sect1 id="plugins.resources"><title>Resources</title>
    <para>
     Resource plugins are meant as a generic way of providing template
     sources or PHP script components to Smarty. Some examples of resources:
     databases, LDAP, shared memory, sockets, and so on.
    </para>

    <para>
     There are a total of 4 functions that need to be registered for each
     type of resource. Every function will receive the requested resource as
     the first parameter and the Smarty object as the last parameter. The
     rest of parameters depend on the function.
    </para>

    <funcsynopsis>
     <funcprototype>
      <funcdef>bool <function>smarty_resource_<replaceable>name</replaceable>_source</function></funcdef>
      <paramdef>string <parameter>$rsrc_name</parameter></paramdef>
      <paramdef>string <parameter>&$source</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
     <funcprototype>
      <funcdef>bool <function>smarty_resource_<replaceable>name</replaceable>_timestamp</function></funcdef>
      <paramdef>string <parameter>$rsrc_name</parameter></paramdef>
      <paramdef>int <parameter>&$timestamp</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
     <funcprototype>
      <funcdef>bool <function>smarty_resource_<replaceable>name</replaceable>_secure</function></funcdef>
      <paramdef>string <parameter>$rsrc_name</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
     <funcprototype>
      <funcdef>bool <function>smarty_resource_<replaceable>name</replaceable>_trusted</function></funcdef>
      <paramdef>string <parameter>$rsrc_name</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
    </funcsynopsis>

    <para>
     The first function is supposed to retrieve the resource. Its second
     parameter is a variable passed by reference where the result should be
     stored. The function is supposed to return <literal>true</literal> if
     it was able to successfully retrieve the resource and
     <literal>false</literal> otherwise.
    </para>

    <para>
     The second function is supposed to retrieve the last modification time
     of the requested resource (as a UNIX timestamp). The second parameter
     is a variable passed by reference where the timestamp should be stored.
     The function is supposed to return <literal>true</literal> if the
     timestamp could be succesfully determined, and <literal>false</literal>
     otherwise.
    </para>

    <para>
     The third function is supposed to return <literal>true</literal> or
     <literal>false</literal>, depending on whether the requested resource
     is secure or not. This function is used only for template resources but
     should still be defined.
    </para>

    <para>
     The fourth function is supposed to return <literal>true</literal> or
     <literal>false</literal>, depending on whether the requested resource
     is trusted or not. This function is used for only for PHP script
     components requested by <command>include_php</command> tag or
     <command>insert</command> tag with <structfield>src</structfield>
     attribute. However, it should still be defined even for template
     resources.
    </para>
    <para>
     See also
     <link linkend="api.register.resource">register_resource()</link>,
     <link linkend="api.unregister.resource">unregister_resource()</link>.
    </para>
    <example>
     <title>resource plugin</title>
     <programlisting>
&lt;?php
/*
 * Smarty plugin
 * ------------------------------------------------------------- 
 * File:     resource.db.php
 * Type:     resource
 * Name:     db
 * Purpose:  Fetches templates from a database
 * -------------------------------------------------------------
 */
function smarty_resource_db_source($tpl_name, &amp;$tpl_source, &amp;$smarty)
{
    // do database call here to fetch your template,
    // populating $tpl_source
    $sql = new SQL;
    $sql->query("select tpl_source
                   from my_table
                  where tpl_name='$tpl_name'");
    if ($sql->num_rows) {
        $tpl_source = $sql->record['tpl_source'];
        return true;
    } else {
        return false;
    }
}

function smarty_resource_db_timestamp($tpl_name, &amp;$tpl_timestamp, &amp;$smarty)
{
    // do database call here to populate $tpl_timestamp.
    $sql = new SQL;
    $sql->query("select tpl_timestamp
                   from my_table
                  where tpl_name='$tpl_name'");
    if ($sql->num_rows) {
        $tpl_timestamp = $sql->record['tpl_timestamp'];
        return true;
    } else {
        return false;
    }
}

function smarty_resource_db_secure($tpl_name, &amp;$smarty)
{
    // assume all templates are secure
    return true;
}

function smarty_resource_db_trusted($tpl_name, &amp;$smarty)
{
    // not used for templates
}
?&gt;</programlisting>
    </example>
   </sect1>

   <sect1 id="plugins.inserts"><title>Inserts</title>
    <para>
     Insert plugins are used to implement functions that are invoked by
     <link linkend="language.function.insert"><command>insert</command></link>
     tags in the template.
    </para>
    <funcsynopsis>
     <funcprototype>
      <funcdef>string <function>smarty_insert_<replaceable>name</replaceable></function></funcdef>
      <paramdef>array <parameter>$params</parameter></paramdef>
      <paramdef>object <parameter>&$smarty</parameter></paramdef>
     </funcprototype>
    </funcsynopsis>
    <para>
     The first parameter to the function is an associative array of
     attributes passed to the insert. Either access those values directly,
     e.g. <varname>$params['start']</varname> or use
     <varname>extract($params)</varname> to import them into the symbol
     table.
    </para>
    <para>
     The insert function is supposed to return the result which will be
     substituted in place of the <command>insert</command> tag in the
     template.
    </para>
    <example>
     <title>insert plugin</title>
     <programlisting>
&lt;?php
/*
 * Smarty plugin
 * ------------------------------------------------------------- 
 * File:     insert.time.php
 * Type:     time
 * Name:     time
 * Purpose:  Inserts current date/time according to format
 * -------------------------------------------------------------
 */
function smarty_insert_time($params, &amp;$smarty)
{
    if (empty($params['format'])) {
        $smarty->trigger_error("insert time: missing 'format' parameter");
        return;
    }

    $datetime = strftime($params['format']);
    return $datetime;
}
?&gt;</programlisting>
    </example>
   </sect1>
  </chapter>
 </part>