curt Sat Aug 14 20:17:12 2004 EDT
Added files:
/phpdoc/en/language/oop5 basic.xml
Log:
New basic oop5 documentation
http://cvs.php.net/co.php/phpdoc/en/language/oop5/basic.xml?r=1.1&p=1
Index: phpdoc/en/language/oop5/basic.xml
+++ phpdoc/en/language/oop5/basic.xml
<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.1 $ -->
<sect1 id="language.oop5.basic">
<title>The Basics</title>
<sect1 id="oop5.basic.class">
<title>class</title>
<para>
Every class definition begins with the keyword class, followed by a class
name, which can be any name that isn't a reserverd word in PHP. Followed
by A pair of curly braces, of which contains the definition of the classes
members and methods. Within each method, except for <link
linkend="language.oop5.static">static</link> methods, a psudo variable
<varname>$this</varname> is available. <varname>$this</varname> is a
reference to the same instance that called the method.
</para>
<example>
<title>Simple Class definition</title>
<programlisting role="php">
<![CDATA[
<?php
class SimpleClass {
/* member declaration */
public $var = 'a default value';
/* method declaration */
public function displayVar() {
echo $this->var; /* Echo my own $var value */
}
}
?>
]]>
</programlisting>
</example>
</sect1>
<sect1 id="oop5.basic.new">
<title>new</title>
<para>
To create an instance of an object, a new object must be created and
assigned to a variable. An object will always be assigned when
creating a new object unless the object has a <link
linkend="language.oop5.decon">constructor</link> defined that throws an <link
linkend="language.oop5.exceptions">exception</link> on error.
</para>
<example>
<title>Creating an instance</title>
<programlisting role="php">
<![CDATA[
<?php
$instance = new SimpleClass()
?>
]]>
</programlisting>
</example>
<para>
When assigning an already created instance of an object to a new variable, the new
variable
will access the same instance as the object that was assigned. This
behaviour is the same when passing instances to a function. A new instance
of an already created object can be made by <link
linkend="language.oop5.cloning">cloning</link> it.
</para>
<example>
<title>Object Assignment</title>
<programlisting role="php">
<![CDATA[
<?php
$assigned = $instance;
$reference =& $instance;
$instance->var = '$assigned will have this value';
$instance = null; /* $instance and $reference become null */
var_dump($instance);
var_dump($reference);
var_dump($assigned);
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
NULL
NULL
object(SimpleClass)#1 (1) {
["var"]=>
string(30) "$assigned will have this value"
}
]]>
</screen>
</example>
</sect1>
<sect1 id="oop5.basic.extend">
<title>extend</title>
<para>
A class can inherit methods and members of another class by using the
extend keyword in the declaration. It is not possible to extend multiple
classes, a class can only inherit one base class.
</para>
<para>
The inherited methods and members can be overloaded, unless the parent
class has defined a method as <link
linkend="language.oop5.final">final</link>, by redeclaring them
within the same name defined in the parent class. It is possible to access the
overloaded
method or members by referencing them with <link
linkend="lanuguage.oop5.paamayim-nekudotayim">parent::</link>
</para>
<example>
<title>Simple Class Inherintance</title>
<programlisting role="php">
<![CDATA[
<?php
class ExtendClass extends SimpleClass {
/* Redefine the parent method */
function displayVar() {
echo "Extending class\n";
parent::displayVar();
}
}
$extended = new ExtendClass();
$extended->displayVar();
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
Extending class
a default value
]]>
</screen>
</example>
</sect1>
</sect1>
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