php-doc-en/reference/funchand/functions/call-user-func.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.call-user-func" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>call_user_func</refname>
  <refpurpose>Call the callback given by the first parameter</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>mixed</type><methodname>call_user_func</methodname>
   <methodparam><type>callable</type><parameter>callback</parameter></methodparam>
   <methodparam choice="opt"><type>mixed</type><parameter>parameter</parameter></methodparam>
   <methodparam choice="opt"><type>mixed</type><parameter>...</parameter></methodparam>
  </methodsynopsis>
  <para>
   Calls the <parameter>callback</parameter> given by the first parameter and passes
   the remaining parameters as arguments.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>callback</parameter></term>
     <listitem>
      <para>
       The <type>callable</type> to be called.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>parameter</parameter></term>
     <listitem>
      <para>
       Zero or more parameters to be passed to the callback.
      </para>
      <note>
       <para>
        Note that the parameters for <function>call_user_func</function> are
        not passed by reference.
        <example>
         <title><function>call_user_func</function> example and references</title>
         <programlisting role="php">
<![CDATA[
<?php
error_reporting(E_ALL);
function increment(&$var)
{
    $var++;
}

$a = 0;
call_user_func('increment', $a);
echo $a."\n";

// You can use this instead
call_user_func_array('increment', array(&$a));
echo $a."\n";
?>
]]>
         </programlisting>
         &example.outputs;
         <screen>
<![CDATA[
Warning: Parameter 1 to increment() expected to be a reference, value given in …
0
1
]]>
         </screen>
        </example>
       </para>
      </note>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the return value of the callback.
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>5.3.0</entry>
       <entry>
        The interpretation of object oriented keywords like <literal>parent</literal> 
        and <literal>self</literal> has changed. Previously, calling them using the 
        double colon syntax would emit an <constant>E_STRICT</constant> warning because 
        they were interpreted as static.
       </entry>
      </row>
      <row>
       <entry>5.3.0</entry>
       <entry>
        If the called function expects a parameter to be passed by reference, an
        <constant>E_WARNING</constant> is now issued.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>call_user_func</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
function barber($type)
{
    echo "You wanted a $type haircut, no problem\n";
}
call_user_func('barber', "mushroom");
call_user_func('barber', "shave");
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
You wanted a mushroom haircut, no problem
You wanted a shave haircut, no problem
]]>
    </screen>
   </example>
   <example>
    <title><function>call_user_func</function> using namespace name</title>
    <programlisting role="php">
<![CDATA[
<?php

namespace Foobar;

class Foo {
    static public function test() {
        print "Hello world!\n";
    }
}

call_user_func(__NAMESPACE__ .'\Foo::test'); // As of PHP 5.3.0
call_user_func(array(__NAMESPACE__ .'\Foo', 'test')); // As of PHP 5.3.0

?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
Hello world!
Hello world!
]]>
    </screen>
   </example>
   <example>
    <title>Using a class method with <function>call_user_func</function></title>
    <programlisting role="php">
<![CDATA[
<?php

class myclass {
    static function say_hello()
    {
        echo "Hello!\n";
    }
}

$classname = "myclass";

call_user_func(array($classname, 'say_hello'));
call_user_func($classname .'::say_hello'); // As of 5.2.3

$myobject = new myclass();

call_user_func(array($myobject, 'say_hello'));

?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
Hello!
Hello!
Hello!
]]>
    </screen>   
   </example>
   <example>
    <title>Using lambda function with <function>call_user_func</function></title>
    <programlisting role="php">
<![CDATA[
<?php
call_user_func(function($arg) { print "[$arg]\n"; }, 'test'); /* As of PHP 5.3.0 */
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
[test]
]]>
    </screen>   
   </example>
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  &note.func-callback-exceptions;
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>call_user_func_array</function></member>
    <member><function>is_callable</function></member>
    <member>&seealso.callback;</member>
    <member><methodname>ReflectionFunction::invoke</methodname></member>
    <member><methodname>ReflectionMethod::invoke</methodname></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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