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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.13 $ -->
<refentry xml:id="function.is-callable" xmlns="http://docbook.org/ns/docbook">
<refnamediv>
<refname>is_callable</refname>
<refpurpose>
Verify that the contents of a variable can be called as a function
</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<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>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>var</parameter></term>
<listitem>
<para>
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>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>syntax_only</parameter></term>
<listitem>
<para>
If set to &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>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>callable_name</parameter></term>
<listitem>
<para>
Receives the "callable name". In the example below it is
"someClass::someMethod". Note, however, that despite the implication
that someClass::SomeMethod() is a callable static method, this is not
the case.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
Returns &true; if <parameter>var</parameter> is callable, &false;
otherwise.
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title><function>is_callable</function> example</title>
<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>
</example>
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>function_exists</function></member>
<member><function>method_exists</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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