<?xml version="1.0" encoding="utf-8"?>

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<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>

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<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 implicitly 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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