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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="closure.bindto" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<refnamediv>
<refname>Closure::bindTo</refname>
<refpurpose>
Duplicates the closure with a new bound object and class scope
</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis role="Closure">
<modifier>public</modifier> <type class="union"><type>Closure</type><type>null</type></type><methodname>Closure::bindTo</methodname>
<methodparam><type class="union"><type>object</type><type>null</type></type><parameter>newThis</parameter></methodparam>
<methodparam choice="opt"><type class="union"><type>object</type><type>string</type><type>null</type></type><parameter>newScope</parameter><initializer>"static"</initializer></methodparam>
</methodsynopsis>
<para>
Create and return a new <link linkend="functions.anonymous">anonymous
function</link> with the same body and bound variables as this one, but
possibly with a different bound object and a new class scope.
</para>
<para>
The “bound object” determines the value <literal>$this</literal> will
have in the function body and the “class scope” represents a class
which determines which private and protected members the anonymous
function will be able to access. Namely, the members that will be
visible are the same as if the anonymous function were a method of
the class given as value of the <parameter>newScope</parameter>
parameter.
</para>
<para>
Static closures cannot have any bound object (the value of the parameter
<parameter>newThis</parameter> should be &null;), but this method can
nevertheless be used to change their class scope.
</para>
<para>
This method will ensure that for a non-static closure, having a bound
instance will imply being scoped and vice-versa. To this end,
non-static closures that are given a scope but a &null; instance are made
static and non-static non-scoped closures that are given a non-null
instance are scoped to an unspecified class.
</para>
<note>
<para>
If you only want to duplicate the anonymous functions, you can use
<link linkend="language.oop5.cloning">cloning</link> instead.
</para>
</note>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<variablelist>
<varlistentry>
<term><parameter>newThis</parameter></term>
<listitem>
<para>
The object to which the given anonymous function should be bound, or
&null; for the closure to be unbound.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>newScope</parameter></term>
<listitem>
<para>
The class scope to which the closure is to be associated, or
'static' to keep the current one. If an object is given, the type of the
object will be used instead. This determines the visibility of protected
and private methods of the bound object.
It is not allowed to pass (an object of) an internal class as this parameter.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
Returns the newly created <classname>Closure</classname> object
or &null; on failure.
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<example>
<title><function>Closure::bindTo</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
class A
{
private $val;
public function __construct($val)
{
$this->val = $val;
}
public function getClosure()
{
// Returns closure bound to this object and scope
return function() {
return $this->val;
};
}
}
$ob1 = new A(1);
$ob2 = new A(2);
$cl = $ob1->getClosure();
echo $cl(), "\n";
$cl = $cl->bindTo($ob2);
echo $cl(), "\n";
?>
]]>
</programlisting>
&example.outputs.similar;
<screen>
<![CDATA[
1
2
]]>
</screen>
</example>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<simplelist>
<member><link linkend="functions.anonymous">Anonymous functions</link></member>
<member><methodname>Closure::bind</methodname></member>
</simplelist>
</refsect1>
</refentry>
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