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smarty/docs/en/getting-started.xml
2006-12-02 22:19:21 +00:00

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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision$ -->
<part id="getting.started">
<title>Getting Started</title>
<chapter id="what.is.smarty">
<title>What is Smarty?</title>
<para>
Smarty is a template engine for PHP. More specifically, it facilitates a
manageable way to separate application logic and content from its
presentation. This is best described in a situation where the application
programmer and the template designer play different roles, or in most
cases are not the same person.
</para>
<para>
For example, let's say you are creating a web page that is displaying a
newspaper article.
</para>
<itemizedlist>
<listitem><para>
The article <literal>$headline</literal>, <literal>$tagline</literal>,
<literal>$author</literal> and <literal>$body</literal> are
content elements, they contain no information about how they will be
presented. They are <link linkend="api.assign">passed</link> into Smarty
by the application.
</para></listitem>
<listitem><para>Then the
template designer edits the templates and uses a combination of
HTML tags and <link linkend="language.basic.syntax">template tags</link>
to format the presentation of these
<link linkend="language.syntax.variables">variables</link> with elements
such as tables, div's, background colors, font sizes, style sheets, svg etc.
</para></listitem>
<listitem><para>One day
the programmer needs to change the way the article content is retrieved, ie a
change in application logic. This change does not affect the template
designer, the content will still arrive in the template exactly the same.
</para></listitem>
<listitem><para>
Likewise, if the template designer wants to completely redesign the
templates, this would require no change to the application logic.
</para></listitem>
<listitem><para>Therefore,
the programmer can make changes to the application logic without the need
to restructure templates, and the template designer can make changes to
templates without breaking application logic.
</para></listitem>
</itemizedlist>
<para>
One design goal of Smarty is the separation of business logic and
presentation logic.
</para>
<itemizedlist>
<listitem><para>
This means templates can certainly contain logic under
the condition that it is for presentation only. Things such as
<link linkend="language.function.include">including</link>
other templates,
<link linkend="language.function.cycle">alternating</link> table row colors,
<link linkend="language.modifier.upper">upper-casing</link> a variable,
<link linkend="language.function.foreach">looping</link>
over an array of data and <link linkend="api.display">displaying</link> it
are examples of presentation logic.
</para></listitem>
<listitem><para>
This does not mean however that Smarty forces a separation of
business and presentation logic. Smarty has no knowledge of which is which,
so placing business logic in the template is your own doing.
</para></listitem>
<listitem><para>Also, if you
desire <emphasis>no</emphasis> logic in your templates you certainly can
do so by boiling the content down to text and variables only.
</para></listitem>
</itemizedlist>
<para>
One of the unique aspects about Smarty is the template compiling. This
means Smarty reads the template files and creates PHP scripts from them.
Once they are created, they are executed from then on. Therefore there is
no costly template file parsing for each request. Each template can
take full advantage of PHP compiler and cache solutions such as
<ulink url="&url.e-accel;">eAccelerator</ulink>,
<ulink url="&url.ion-accel;">ionCube</ulink>
<ulink url="&url.mmcache-accel;">mmCache</ulink>
or <ulink url="&url.zend;">Zend Accelerator</ulink>
to name a few.
</para>
<para>
<emphasis role="bold">Some of Smarty's features:</emphasis>
</para>
<itemizedlist>
<listitem>
<para>
It is extremely fast.
</para>
</listitem>
<listitem>
<para>
It is efficient since the PHP parser does the dirty work.
</para>
</listitem>
<listitem>
<para>
No template parsing overhead, only compiles once.
</para>
</listitem>
<listitem>
<para>
It is smart about <link linkend="variable.compile.check">recompiling</link>
only the template files that have changed.
</para>
</listitem>
<listitem>
<para>
You can easily create your own custom <link
linkend="language.custom.functions">functions</link>
and <link linkend="language.modifiers">variable modifiers</link>, so the
template language is extremely extensible.
</para>
</listitem>
<listitem>
<para>
Configurable template
<link linkend="variable.left.delimiter">{delimiter}</link> tag
syntax, so you can use
<literal>{$foo}</literal>, <literal>{{$foo}}</literal>,
<literal>&lt;!--{$foo}--&gt;</literal>, etc.
</para>
</listitem>
<listitem>
<para>
The <link linkend="language.function.if">
<literal>{if}..{elseif}..{else}..{/if}</literal></link>
constructs are passed to the
PHP parser, so the <literal>{if...}</literal> expression syntax can be as
simple or as complex an evaluation as you like.
</para>
</listitem>
<listitem>
<para>
Allows unlimited nesting of <link linkend="language.function.section">
<varname>sections</varname></link>, <varname>if's</varname> etc.
</para>
</listitem>
<listitem>
<para>
It is possible to
<link linkend="language.function.php">embed PHP code</link>
right in your template files, although
this may not be needed (nor recommended) since the engine is so
<link linkend="plugins">customizable</link>.
</para>
</listitem>
<listitem>
<para>
Built-in <link linkend="caching">caching</link> support
</para>
</listitem>
<listitem>
<para>
Arbitrary <link linkend="template.resources">template</link> sources
</para>
</listitem>
<listitem>
<para>
Custom <link
linkend="section.template.cache.handler.func">cache handling</link>
functions
</para>
</listitem>
<listitem>
<para>
<link linkend="plugins">Plugin</link> architecture
</para>
</listitem>
</itemizedlist>
</chapter>
<chapter id="installation">
<title>Installation</title>
<sect1 id="installation.requirements">
<title>Requirements</title>
<para>
Smarty requires a web server running PHP 4.0.6 or greater.
</para>
</sect1>
<sect1 id="installing.smarty.basic">
<title>Basic Installation</title>
<para>
Install the Smarty library files which are in the
<filename class="directory">/libs/</filename> sub directory of
the distribution. These are <filename>.php</filename> files that you
SHOULD NOT edit. They are shared among all applications and only get
changed when you upgrade to a new version of Smarty.
</para>
<para>In the examples below the Smarty tarball has been unpacked to:
<itemizedlist>
<listitem><para>
<filename class="directory">/usr/local/lib/Smarty-v.e.r/</filename> for *nix
machines</para></listitem>
<listitem><para> and
<filename class="directory">c:\webroot\libs\Smarty-v.e.r\</filename> for the
windows enviroment.</para></listitem>
</itemizedlist>
</para>
<example>
<title>Required Smarty library files</title>
<screen>
<![CDATA[
Smarty-v.e.r/
libs/
Smarty.class.php
Smarty_Compiler.class.php
Config_File.class.php
debug.tpl
internals/*.php (all of them)
plugins/*.php (all of them)
]]>
</screen>
</example>
<para>
Smarty uses a PHP <ulink url="&url.php-manual;define">constant</ulink>
named <link linkend="constant.smarty.dir"><constant>SMARTY_DIR</constant>
</link> which is the <emphasis role="bold">full system file path</emphasis>
to the Smarty <filename>libs/</filename> directory.
Basically, if your application can find the
<filename>Smarty.class.php</filename> file, you do not need to set the
<link linkend="constant.smarty.dir"><constant>SMARTY_DIR</constant></link>
as Smarty will figure it out on its own.
Therefore, if
<filename>Smarty.class.php</filename> is not in your
<ulink url="&url.php-manual;ini.core.php#ini.include-path">include_path</ulink>,
or you do not supply an absolute path to it in your application,
then you must define <constant>SMARTY_DIR</constant> manually.
<constant>SMARTY_DIR</constant> <emphasis role="bold">must include a
trailing slash/</emphasis>.
</para>
<informalexample>
<para>
Here's how you create an instance of Smarty in your PHP scripts:
</para>
<programlisting role="php">
<![CDATA[
<?php
// NOTE: Smarty has a capital 'S'
require_once('Smarty.class.php');
$smarty = new Smarty();
?>
]]>
</programlisting>
</informalexample>
<para>
Try running the above script. If you get an error saying the
<filename>Smarty.class.php</filename> file could not be found, you need to
do one of the following:
</para>
<example>
<title>Set SMARTY_DIR constant manually</title>
<programlisting role="php">
<![CDATA[
<?php
// *nix style (note capital 'S')
define('SMARTY_DIR', '/usr/local/lib/Smarty-v.e.r/libs/');
// windows style
define('SMARTY_DIR', 'c:/webroot/libs/Smarty-v.e.r/libs/');
// hack version example that works on both *nix and windows
// Smarty is assumend to be in 'includes/' dir under current script
define('SMARTY_DIR',str_replace("\\","/",getcwd()).'/includes/Smarty-v.e.r/libs/');
require_once(SMARTY_DIR . 'Smarty.class.php');
$smarty = new Smarty();
?>
]]>
</programlisting>
</example>
<example>
<title>Supply absolute path to library file</title>
<programlisting role="php">
<![CDATA[
<?php
// *nix style (note capital 'S')
require_once('/usr/local/lib/Smarty-v.e.r/libs/Smarty.class.php');
// windows style
require_once('c:/webroot/libs/Smarty-v.e.r/libs/Smarty.class.php');
$smarty = new Smarty();
?>
]]>
</programlisting>
</example>
<example>
<title>Add the library path to the <filename>php.ini</filename> file</title>
<programlisting role="php">
<![CDATA[
;;;;;;;;;;;;;;;;;;;;;;;;;
; Paths and Directories ;
;;;;;;;;;;;;;;;;;;;;;;;;;
; *nix: "/path1:/path2"
include_path = ".:/usr/share/php:/usr/local/lib/Smarty-v.e.r/libs/"
; Windows: "\path1;\path2"
include_path = ".;c:\php\includes;c:\webroot\libs\Smarty-v.e.r\libs\"
]]>
</programlisting>
</example>
<example>
<title>Appending the include path in a php script with
<literal><ulink url="&url.e-accel;">ini_set()</ulink></literal></title>
<programlisting role="php">
<![CDATA[
<?php
// *nix
ini_set('include_path', ini_get('include_path').PATH_SEPARATOR.'/usr/local/lib/Smarty-v.e.r/libs/');
// windows
ini_set('include_path', ini_get('include_path').PATH_SEPARATOR.'c:/webroot/lib/Smarty-v.e.r/libs/');
?>
]]>
</programlisting>
</example>
<para>
Now that the library files are in place, it's time to setup the Smarty
directories for your application:</para>
<itemizedlist>
<listitem><para>
Smarty requires four directories which
are by default named <filename class="directory">templates/</filename>,
<filename class="directory">templates_c/</filename>, <filename
class="directory">configs/</filename> and <filename
class="directory">cache/</filename>
</para></listitem>
<listitem><para>Each of these are definable by the
Smarty class properties
<link linkend="variable.template.dir">
<varname>$template_dir</varname></link>,
<link linkend="variable.compile.dir">
<varname>$compile_dir</varname></link>,
<link linkend="variable.config.dir">
<varname>$config_dir</varname></link>, and
<link linkend="variable.cache.dir">
<varname>$cache_dir</varname></link> respectively
</para></listitem>
<listitem><para>
It is highly recommended
that you setup a separate set of these directories for each application
that will use Smarty
</para></listitem>
</itemizedlist>
<para>
For our installation example, we will be setting up the Smarty environment
for a guest book application. We picked an application only for the purpose
of a directory naming convention. You can use the same environment for any
application, just replace <literal>guestbook/</literal> with
the name of your application.
</para>
<example>
<title>What the file structure looks like</title>
<screen>
<![CDATA[
/usr/local/lib/Smarty-v.e.r/libs/
Smarty.class.php
Smarty_Compiler.class.php
Config_File.class.php
debug.tpl
internals/*.php
plugins/*.php
/web/www.example.com/
guestbook/
templates/
index.tpl
templates_c/
configs/
cache/
htdocs/
index.php
]]>
</screen>
</example>
<para>
Be sure that you know the location of your web server's document root as a
file path. In the following examples, the document root is <filename
class="directory">/web/www.example.com/guestbook/htdocs/</filename>.
The Smarty
directories are only accessed by the Smarty library and never accessed
directly by the web browser. Therefore to avoid any security concerns, it
is recommended (but not mandatory) to place these directories
<emphasis>outside</emphasis> of the web server's document root.
</para>
<para>
You will need as least one file under your document root, and that is the
script accessed by the web browser. We will name our script
<filename>index.php</filename>, and place it in a subdirectory under the
document root <filename class="directory">/htdocs/</filename>.
</para>
<para>
Smarty will need <emphasis role="bold">write access</emphasis>
(windows users please ignore) to the
<link linkend="variable.compile.dir">
<parameter>$compile_dir</parameter></link> and
<link linkend="variable.cache.dir">
<parameter>$cache_dir</parameter></link> directories
(<filename class="directory">templates_c/</filename> and
<filename class="directory">cache/</filename>), so be sure the web server
user account can write to them.
<note><para>This is usually user <quote>nobody</quote> and
group <quote>nobody</quote>. For OS X users,
the default is user <quote>www</quote> and group <quote>www</quote>.
If you are using Apache, you can look in your
<filename>httpd.conf</filename> file to see
what user and group are being used.</para></note>
</para>
<example>
<title>Permissions and making directories writable</title>
<programlisting role="shell">
<![CDATA[
chown nobody:nobody /web/www.example.com/guestbook/templates_c/
chmod 770 /web/www.example.com/guestbook/templates_c/
chown nobody:nobody /web/www.example.com/guestbook/cache/
chmod 770 /web/www.example.com/guestbook/cache/
]]>
</programlisting>
</example>
<note>
<title>Note</title>
<para>
<literal>chmod 770</literal> will be fairly tight security, it only allows
user <quote>nobody</quote> and group <quote>nobody</quote> read/write access
to the directories. If you would like to open up read access to anyone
(mostly for your own convenience of viewing
these files), you can use <literal>775</literal> instead.
</para>
</note>
<para>
We need to create the <filename>index.tpl</filename> file that Smarty will
display. This needs to be located in the <link linkend="variable.template.dir">
<parameter>$template_dir</parameter></link>.
</para>
<example>
<title>/web/www.example.com/guestbook/templates/index.tpl</title>
<screen>
<![CDATA[
{* Smarty *}
Hello {$name}, welcome to Smarty!
]]>
</screen>
</example>
<note>
<title>Technical Note</title>
<para>
<literal>{* Smarty *}</literal> is a template
<link linkend="language.syntax.comments">comment</link>.
It is not required, but it is good
practice to start all your template files with this comment. It makes
the file easy to recognize regardless of the file extension. For
example, text editors could recognize the file and turn on special
syntax highlighting.
</para>
</note>
<para>
Now lets edit <filename>index.php</filename>. We'll create an instance of Smarty,
<link linkend="api.assign"><varname>assign()</varname></link> a
template variable and <link linkend="api.display"><varname>display()</varname></link>
the <filename>index.tpl</filename> file.
</para>
<example>
<title>Editing /web/www.example.com/docs/guestbook/index.php</title>
<programlisting role="php">
<![CDATA[
<?php
require_once(SMARTY_DIR . 'Smarty.class.php');
$smarty = new Smarty();
$smarty->template_dir = '/web/www.example.com/guestbook/templates/';
$smarty->compile_dir = '/web/www.example.com/guestbook/templates_c/';
$smarty->config_dir = '/web/www.example.com/guestbook/configs/';
$smarty->cache_dir = '/web/www.example.com/guestbook/cache/';
$smarty->assign('name','Ned');
//** un-comment the following line to show the debug console
//$smarty->debugging = true;
$smarty->display('index.tpl');
?>
]]>
</programlisting>
</example>
<note>
<title>Note</title>
<para>
In our example, we are setting absolute paths to all of the Smarty
directories. If <filename
class="directory">/web/www.example.com/guestbook/</filename> is
within your PHP include_path, then these settings are not necessary.
However, it is more efficient and (from experience) less error-prone to
set them to absolute paths. This ensures that Smarty is getting files
from the directories you intended.
</para>
</note>
<para>
Now naviagate to the <filename>index.php</filename> file with the web browser.
You should see <emphasis>"Hello Ned, welcome to Smarty!"</emphasis>
</para>
<para>
You have completed the basic setup for Smarty!
</para>
</sect1>
<sect1 id="installing.smarty.extended">
<title>Extended Setup</title>
<para>
This is a continuation of the <link
linkend="installing.smarty.basic">basic installation</link>, please read
that first!
</para>
<para>
A slightly more flexible way to setup Smarty is to
<ulink url="&url.php-manual;ref.classobj">extend the class</ulink> and
initialize your Smarty environment. So instead of repeatedly setting
directory paths, assigning the same vars, etc., we can do that in one place.
</para>
<para>
Lets create a new directory <filename
class="directory">/php/includes/guestbook/</filename>
and make a new file called <filename>setup.php</filename>. In our example
environment, <filename class="directory">/php/includes</filename> is in our
<literal>include_path</literal>.
Be sure you set this up too, or use absolute file paths.
</para>
<example>
<title>/php/includes/guestbook/setup.php</title>
<programlisting role="php">
<![CDATA[
<?php
// load Smarty library
require('Smarty.class.php');
// The setup.php file is a good place to load
// required application library files, and you
// can do that right here. An example:
// require('guestbook/guestbook.lib.php');
class Smarty_GuestBook extends Smarty {
function Smarty_GuestBook()
{
// Class Constructor.
// These automatically get set with each new instance.
$this->Smarty();
$this->template_dir = '/web/www.example.com/guestbook/templates/';
$this->compile_dir = '/web/www.example.com/guestbook/templates_c/';
$this->config_dir = '/web/www.example.com/guestbook/configs/';
$this->cache_dir = '/web/www.example.com/guestbook/cache/';
$this->caching = true;
$this->assign('app_name', 'Guest Book');
}
}
?>
]]>
</programlisting>
</example>
<para>
Now lets alter the <filename>index.php</filename> file to use
<filename>setup.php</filename>:
</para>
<example>
<title>/web/www.example.com/guestbook/htdocs/index.php</title>
<programlisting role="php">
<![CDATA[
<?php
require('guestbook/setup.php');
$smarty = new Smarty_GuestBook();
$smarty->assign('name','Ned');
$smarty->display('index.tpl');
?>
]]>
</programlisting>
</example>
<para>
Now you see it is quite simple to bring up an instance of Smarty, just use
<literal>Smarty_GuestBook()</literal> which automatically initializes everything for our
application.
</para>
</sect1>
</chapter>
</part>
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