90 lines
2.3 KiB
HTML
90 lines
2.3 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<title>Extra Variables</title>
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<link href="style.css" rel="stylesheet" type="text/css">
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</head>
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<body background="images/back.gif">
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<!--START-->
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<h3>Extra variables</h3>
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You create new variables by assigning a value to them (no need to declare
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them first). If you simply use a variable name, the variable will be
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stored with the current object instance only. So don't expect to find it
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when dealing with another object (or another instance of the same object)
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later. You can also set and read variables in other objects by putting the
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object name with a dot before the variable name.
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<p>
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To create global variables, that are visible to all object instances,
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precede them with the word <tt>global</tt> and a dot. So for example you
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can write:
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<p>
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<blockquote>
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<pre>
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{
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<b>if</b> (<b>global</b>.doit)
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{
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// do something
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<b>global</b>.doit = false;
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}
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}
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</pre>
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</blockquote>
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<p>
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Alternatively you can declare the variables as being global.
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This declaration looks as follows.
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<p>
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<blockquote>
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<pre><b>globalvar</b> <varname1>,<varname2>,<varname3>, ... ;</pre>
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</blockquote>
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<p>
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Once this declaration has been executed, the variable is always treated as global without
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the need to put the word <tt>global</tt> and a dot in front of it. It only needs to
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be declared once in a piece of code that is executed. After that in all other
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places the variable is considered as being global.
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<p>
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Sometimes you want variables only within the current piece of code or
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script. In this way you avoid wasting memory and you are sure there is no
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naming conflict. It is also faster than using global variables. To achieve
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this you must declare the variables at the beginning of the piece of code
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using the keyword var. This declaration looks as follows.
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<p>
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<blockquote>
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<pre><b>var</b> <varname1>,<varname2>,<varname3>, ... ;</pre>
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</blockquote>
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<p>
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For example, you can write:
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<p>
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<blockquote>
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<pre>
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{
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<b>var</b> xx,yy;
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xx = x+10;
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yy = y+10;
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instance_create(xx,yy,ball);
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}
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</pre>
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</blockquote>
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<!--END-->
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</body>
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</html>
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<!-- KEYWORDS
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global variables
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local variables
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declaring variables
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var
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globalvar
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--> |