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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<reference xml:id="class.stringable" role="class" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude">
<title>The Stringable interface</title>
<titleabbrev>Stringable</titleabbrev>
<partintro>
<!-- {{{ Stringable intro -->
<section xml:id="stringable.intro">
&reftitle.intro;
<para>
The <interfacename>Stringable</interfacename> interface denotes a class as
having a <link linkend="object.tostring">__toString()</link> method. Unlike most interfaces,
<interfacename>Stringable</interfacename> is implicitly present on any class that
has the magic <link linkend="object.tostring">__toString()</link> method defined, although it
can and should be declared explicitly.
</para>
<para>
Its primary value is to allow functions to type check against the union
type <literal>string|Stringable</literal> to accept either a string primitive
or an object that can be cast to a string.
</para>
</section>
<!-- }}} -->
<section xml:id="stringable.synopsis">
&reftitle.interfacesynopsis;
<!-- {{{ Synopsis -->
<classsynopsis class="interface">
<oointerface>
<interfacename>Stringable</interfacename>
</oointerface>
<classsynopsisinfo role="comment">&Methods;</classsynopsisinfo>
<xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.stringable')/db:refentry/db:refsect1[@role='description']/descendant::db:methodsynopsis[@role='Stringable'])">
<xi:fallback/>
</xi:include>
</classsynopsis>
<!-- }}} -->
</section>
<section xml:id="stringable.examples">
<title>Stringable Examples</title>
<para>
<example xml:id="stringable.basic-example">
<title>Basic Stringable Usage</title>
<simpara>This uses <link linkend="language.oop5.decon.constructor.promotion">constructor property promotion</link>.</simpara>
<programlisting role="php">
<![CDATA[
<?php
class IPv4Address implements Stringable {
public function __construct(
private string $oct1,
private string $oct2,
private string $oct3,
private string $oct4,
) {}
public function __toString(): string {
return "$this->oct1.$this->oct2.$this->oct3.$this->oct4";
}
}
function showStuff(string|Stringable $value) {
// For a Stringable, this will implicitliy call __toString().
print $value;
}
$ip = new IPv4Address('123', '234', '42', '9');
showStuff($ip);
?>
]]>
</programlisting>
&example.outputs.similar;
<screen>
<![CDATA[
123.234.42.9
]]>
</screen>
</example>
</para>
</section>
</partintro>
&language.predefined.stringable.tostring;
</reference>
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