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Added definitions for get_class, get_parent_class, class_exists,

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is_subclass_of, get_declared_classes.
Added also an example on how to use the functions in this section.


git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@27975 c90b9560-bf6c-de11-be94-00142212c4b1
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Jesus M. Castagnetto 2000-07-10 04:29:52 +00:00
parent e08f59fea4
commit 06799b318b
1 changed files with 284 additions and 2 deletions
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286
functions/classobj.xml
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@ -2,6 +2,213 @@
<title>Class/Object Functions</title>
<titleabbrev>Classes/Objects</titleabbrev>
<partintro>
<sect1 id="classobj.partintro">
<title>Introduction</title>
<sect2 id="classobj.intro">
<title>About</title>
<para>
These functions allow you to obtain information about classes
and instance objects. You can obtain the name of the class to
which a object belongs, as well as its member properties and
methods. Using this functions, you can find out not only the
class membership of an object, but also its parentage (i.e.
what class is the object class extending).
</para>
</sect2>
<sect2>
<title>An example of use</title>
<para>
In this example, we first define a base class and an extension
of the class. The base class describes a general vegetable,
whether it is edible or not and what is its color. The subclass
<varname>Spinach</varname> adds a method to cook it and another to
find out if it is cooked.
</para>
<para>
<example>
<title>classes.inc</title>
<programlisting role="php">
&lt;?php
// base class with member properties and methods
class Vegetable {
var $edible;
var $color;
function Vegetable( $edible, $color=&quot;green&quot; ) {
$this-&gt;edible = $edible;
$this-&gt;color = $color;
}
function is_edible() {
return $this-&gt;edible;
}
function what_color() {
return $this-&gt;color;
}
} // end of class Vegetable
// extends the base class
class Spinach extends Vegetable {
var $cooked = false;
function Spinach() {
$this-&gt;Vegetable( true, &quot;green&quot; );
}
function cook_it() {
$this-&gt;cooked = true;
}
function is_cooked() {
return $this-&gt;cooked;
}
} // end of class Spinach
?&gt;
</programlisting>
</example>
</para>
<para>
We then instantiate 2 objects from these classes and print out
information about them, including their class parentage.
We also define some utility functions, mainly to have a nice printout
of the variables.
</para>
<para>
<example>
<title>test_script.php</title>
<programlisting role="php">
&lt;pre&gt;
&lt;?php
include &quot;classes.inc&quot;;
// utility functions
function print_vars($obj) {
$arr = get_object_vars($obj);
while (list($prop, $val) = each($arr))
echo &quot;\t$prop = $val\n&quot;;
}
function print_methods($obj) {
$arr = get_class_methods(get_class($obj));
foreach ($arr as $method)
echo &quot;\tfunction $method()\n&quot;;
}
function class_parentage($obj, $class) {
global $$obj;
if (is_subclass_of($$obj, $class)) {
echo &quot;Object $obj belongs to class &quot;.get_class($$obj);
echo &quot; a subclass of $class\n&quot;;
} else {
echo &quot;Object $obj does not belong to a subclass of $class\n&quot;;
}
}
// instantiate 2 objects
$veggie = new Vegetable(true,&quot;blue&quot;);
$leafy = new Spinach();
// print out information about objects
echo &quot;veggie: CLASS &quot;.get_class($veggie).&quot;\n&quot;;
echo &quot;leafy: CLASS &quot;.get_class($leafy);
echo &quot;, PARENT &quot;.get_parent_class($leafy).&quot;\n&quot;;
// show veggie properties
echo &quot;\nveggie: Properties\n&quot;;
print_vars($veggie);
// and leafy methods
echo &quot;\nleafy: Methods\n&quot;;
print_methods($leafy);
echo &quot;\nParentage:\n&quot;;
class_parentage(&quot;leafy&quot;, &quot;Spinach&quot;);
class_parentage(&quot;leafy&quot;, &quot;Vegetable&quot;);
?&gt;
&lt;/pre&gt;
</programlisting>
</example>
</para>
<para>
One important thing to note in the example above is that
the object <varname>$leafy</varname> is an instance of the class
<varname>Spinach</varname> which is a subclass of
<varname>Vegetable</varname>,
therefore the last part of the script above will output:
</para>
<para>
<informalexample>
<programlisting>
[...]
Parentage:
Object leafy does not belong to a subclass of Spinach
Object leafy belongs to class spinach a subclass of Vegetable
</programlisting>
</informalexample>
</para>
</sect2>
</sect1>
</partintro>
<refentry id="function.get-class">
<refnamediv>
<refname>get_class</refname>
<refpurpose>Returns the name of the class of an object</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<funcsynopsis>
<funcprototype>
<funcdef>string <function>get_class</function></funcdef>
<paramdef>object <parameter>obj</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<para>
This function returns the name of the class of which the
object <parameter>obj</parameter> is an instance.
</para>
<simpara>
See also <function>get_parent_class</function>
</simpara>
</refsect1>
</refentry>
<refentry id="function.get-parent-class">
<refnamediv>
<refname>get_parent_class</refname>
<refpurpose>Returns the name of the parent class of an object</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<funcsynopsis>
<funcprototype>
<funcdef>string <function>get_parent_class</function></funcdef>
<paramdef>object <parameter>obj</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<para>
This function returns the name of the parent class to
the class of which the object <parameter>obj</parameter>
is an instance.
</para>
<simpara>
See also <function>get_class</function>
</simpara>
</refsect1>
</refentry>
<refentry id="function.get-class-methods">
<refnamediv>
<refname>get_class_methods</refname>
@ -47,7 +254,7 @@
<refentry id="function.get-object-vars">
<refnamediv>
<refname>get_object_vars</refname>
<refpurpose>Returns an array of object properties</refpurpose>
<refpurpose>Returns an associative array of object properties</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
@ -58,12 +265,58 @@
</funcprototype>
</funcsynopsis>
<para>
This function returns an array of object properties for the
This function returns an associative array of object properties for the
specified object <parameter>obj</parameter>.
</para>
</refsect1>
</refentry>
<refentry id="function.is-subclass-of">
<refnamediv>
<refname>is_subclass_of</refname>
<refpurpose>
Determines if an object belongs to a subclass
of the specified class
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<funcsynopsis>
<funcprototype>
<funcdef>bool <function>is_subclass_of</function></funcdef>
<paramdef>object <parameter>obj</parameter></paramdef>
<paramdef>string <parameter>superclass</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<para>
This function returns true if the object <parameter>obj</parameter>,
belongs to a class which is a subclass of
<parameter>superclass</parameter>, false otherwise.
</para>
</refsect1>
</refentry>
<refentry id="function.class-exists">
<refnamediv>
<refname>class_exists</refname>
<refpurpose>Checks if the class has been defined</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<funcsynopsis>
<funcprototype>
<funcdef>bool <function>class_exists</function></funcdef>
<paramdef>string <parameter>class_name</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<para>
This function returns true if the class given by
<parameter>class_name</parameter> has been defined,
false otherwise.
</para>
</refsect1>
</refentry>
<refentry id="function.method-exists">
<refnamediv>
<refname>method_exists</refname>
@ -86,6 +339,35 @@
</refsect1>
</refentry>
<refentry id="function.get-declared-classes">
<refnamediv>
<refname>get_declared_classes</refname>
<refpurpose>Returns an array with the name of the defined classes</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<funcsynopsis>
<funcprototype>
<funcdef>array <function>get_declared_classes</function></funcdef>
<paramdef>void</paramdef>
</funcprototype>
</funcsynopsis>
<para>
This function returns an array of the names of the declared classes
in the current script.
</para>
<note>
<para>
In PHP 4.0.1pl2, three extra classes are returned at the beginning of
the array: <varname>stdClass</varname> (defined in Zend/zend.c),
<varname>OverloadedTestClass</varname> (defined in
ext/standard/basic_functions.c) and <varname>Directory</varname>
(defined in ext/standard/dir.c).
</para>
</note>
</refsect1>
</refentry>
</reference>
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