mirror of
https://github.com/sigmasternchen/php-doc-en
synced 2025-03-29 23:38:56 +00:00
feaaed262e
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@312632 c90b9560-bf6c-de11-be94-00142212c4b1
99 lines
3.1 KiB
XML
99 lines
3.1 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
|
|
<!-- $Revision$ -->
|
|
<sect1 xml:id="language.oop5.traits" xmlns="http://docbook.org/ns/docbook">
|
|
<title>Traits</title>
|
|
|
|
<para>
|
|
Traits is a mechanism for code reuse in single inheritance languages such as
|
|
PHP. A Trait is intended to reduce some limitations of single inheritance by
|
|
enabling a developer to reuse sets of methods freely in several independent
|
|
classes living in different class hierarchies. The semantics of the combination
|
|
of Traits and classes is defined in a way which reduces complexity, and avoids
|
|
the typical problems associated with multiple inheritance and Mixins.
|
|
</para>
|
|
<para>
|
|
A Trait is similar to a class, but only intended to group functionality in a
|
|
fine-grained and consistent way. It is not possible to instantiate a Trait on
|
|
its own. It is an addition to traditional inheritance and enables horizontal
|
|
composition of behavior; that is, the application of class members without
|
|
requiring inheritance.
|
|
</para>
|
|
|
|
<sect2 xml:id="language.oop5.traits.precedence">
|
|
<title>Precedence</title>
|
|
<para>
|
|
An inherited member from a base class is overridden by a member inserted
|
|
by a Trait. The precedence order is that members from the current class
|
|
override Trait methods, which in return override inherited methods.
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 xml:id="language.oop5.traits.multiple">
|
|
<title>Multiple Traits</title>
|
|
<para>
|
|
Multiple Traits can be inserted into a class by listing them in the use
|
|
statement, separated by commas.
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 xml:id="language.oop5.traits.conflict">
|
|
<title>Conflict Resolution</title>
|
|
<para>
|
|
If two Traits insert a member by the same name, a fatal error is produced,
|
|
if the conflict is not explicitly resolved.
|
|
</para>
|
|
<para>
|
|
To resolve conflicted naming among Traits, one can use the <literal>insteadof</literal>
|
|
operator to explicitly define the precedence between said Traits. Or,
|
|
one can use the <literal>as</literal> operator to alias the conflicting
|
|
member name(s).
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 xml:id="language.oop5.traits.examples">
|
|
&reftitle.examples;
|
|
<example xml:id="language.oop5.traits.examples.ex1">
|
|
<title>Trait example</title>
|
|
<programlisting role="php">
|
|
<![CDATA[
|
|
<?php
|
|
trait ezcReflectionReturnInfo {
|
|
function getReturnType() { /*1*/ }
|
|
function getReturnDescription() { /*2*/ }
|
|
}
|
|
|
|
class ezcReflectionMethod extends ReflectionMethod {
|
|
use ezcReflectionReturnInfo;
|
|
/* ... */
|
|
}
|
|
|
|
class ezcReflectionFunction extends ReflectionFunction {
|
|
use ezcReflectionReturnInfo;
|
|
/* ... */
|
|
}
|
|
?>
|
|
]]>
|
|
</programlisting>
|
|
</example>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<!-- Keep this comment at the end of the file
|
|
Local variables:
|
|
mode: sgml
|
|
sgml-omittag:t
|
|
sgml-shorttag:t
|
|
sgml-minimize-attributes:nil
|
|
sgml-always-quote-attributes:t
|
|
sgml-indent-step:1
|
|
sgml-indent-data:t
|
|
indent-tabs-mode:nil
|
|
sgml-parent-document:nil
|
|
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
|
|
sgml-exposed-tags:nil
|
|
sgml-local-catalogs:nil
|
|
sgml-local-ecat-files:nil
|
|
End:
|
|
vim600: syn=xml fen fdm=syntax fdl=2 si
|
|
vim: et tw=78 syn=sgml
|
|
vi: ts=1 sw=1
|