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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.10 $ -->
<!-- splitted from ./en/functions/var.xml, last change in rev 1.87 -->
<refentry id="function.is-callable">
<refnamediv>
<refname>is_callable</refname>
<refpurpose>
Verify that the contents of a variable can be called as a function
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<methodsynopsis>
<type>bool</type><methodname>is_callable</methodname>
<methodparam><type>mixed</type><parameter>var</parameter></methodparam>
<methodparam choice="opt"><type>bool</type><parameter>syntax_only</parameter></methodparam>
<methodparam choice="opt"><type>string</type><parameter role="reference">callable_name</parameter></methodparam>
</methodsynopsis>
<para>
Verify that the contents of a variable can be called as a function.
This can check that a simple variable contains the name of a valid
function, or that an array contains a properly encoded object and
function name.
</para>
<para>
The <parameter>var</parameter> parameter can be either the name of a function stored in
a string variable, or an object and the name of a method within the
object, like this:
<screen>array($SomeObject, 'MethodName')</screen>
</para>
<para>
If the <parameter>syntax_only</parameter> argument is &true; the
function only verifies that <parameter>var</parameter> might be a
function or method. It will only reject simple variables that are
not strings, or an array that does not have a valid structure to be
used as a callback. The valid ones are supposed to have only 2
entries, the first of which is an object or a string, and the
second a string.
</para>
<para>
The <parameter>callable_name</parameter> argument receives the
"callable name". In the example below it's
"someClass:someMethod". Note, however, that despite the
implication that someClass::SomeMethod() is a callable static
method, this is not the case.
</para>
<informalexample>
<programlisting role="php">
<![CDATA[
<?php
// How to check a variable to see if it can be called
// as a function.
//
// Simple variable containing a function
//
function someFunction()
{
}
$functionVariable = 'someFunction';
var_dump(is_callable($functionVariable, false, $callable_name)); // bool(true)
echo $callable_name, "\n"; // someFunction
//
// Array containing a method
//
class someClass {
function someMethod()
{
}
}
$anObject = new someClass();
$methodVariable = array($anObject, 'someMethod');
var_dump(is_callable($methodVariable, true, $callable_name)); // bool(true)
echo $callable_name, "\n"; // someClass:someMethod
?>
]]>
</programlisting>
</informalexample>
<para>
See also <function>function_exists</function> and
<function>method_exists</function>.
</para>
</refsect1>
</refentry>
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