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Fixed bug #51381 (Clarify class definition order importance for multiple levels of inheritance)
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@304561 c90b9560-bf6c-de11-be94-00142212c4b1
This commit is contained in:
Kalle Sommer Nielsen
parent
1d0012d759
commit
962b413925
1 changed files with 91 additions and 81 deletions
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@ -1,81 +1,91 @@
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<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<sect1 xml:id="language.oop5.inheritance" xmlns="http://docbook.org/ns/docbook">
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<title>Object Inheritance</title>
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<para>
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Inheritance is a well-established programming principle, and PHP makes use
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of this principle in its object model. This principle will affect the way
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many classes and objects relate to one another.
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</para>
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<para>
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For example, when you extend a class, the subclass inherits all of the
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public and protected methods from the parent class. Unless a class overrides
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those methods, they will retain their original functionality.
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</para>
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<para>
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This is useful for defining and abstracting functionality, and permits the
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implementation of additional functionality in similar objects without the
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need to reimplement all of the shared functionality.
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</para>
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<sect2 xml:id="language.oop5.inheritance.examples">
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<example xml:id="language.oop5.inheritance.examples.ex1">
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<title>Inheritance Example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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class foo
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{
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public function printItem($string)
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{
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echo 'Foo: ' . $string . PHP_EOL;
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}
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public function printPHP()
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{
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echo 'PHP is great.' . PHP_EOL;
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}
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}
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class bar extends foo
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{
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public function printItem($string)
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{
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echo 'Bar: ' . $string . PHP_EOL;
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}
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}
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$foo = new foo();
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$bar = new bar();
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$foo->printItem('baz'); // Output: 'Foo: baz'
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$foo->printPHP(); // Output: 'PHP is great'
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$bar->printItem('baz'); // Output: 'Bar: baz'
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$bar->printPHP(); // Output: 'PHP is great'
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?>
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]]>
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</programlisting>
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</example>
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</sect2>
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</sect1>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<sect1 xml:id="language.oop5.inheritance" xmlns="http://docbook.org/ns/docbook">
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<title>Object Inheritance</title>
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<para>
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Inheritance is a well-established programming principle, and PHP makes use
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of this principle in its object model. This principle will affect the way
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many classes and objects relate to one another.
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</para>
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<para>
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For example, when you extend a class, the subclass inherits all of the
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public and protected methods from the parent class. Unless a class overrides
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those methods, they will retain their original functionality.
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</para>
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<para>
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This is useful for defining and abstracting functionality, and permits the
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implementation of additional functionality in similar objects without the
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need to reimplement all of the shared functionality.
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</para>
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<sect2 xml:id="language.oop5.inheritance.examples">
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<example xml:id="language.oop5.inheritance.examples.ex1">
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<title>Inheritance Example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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class foo
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{
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public function printItem($string)
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{
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echo 'Foo: ' . $string . PHP_EOL;
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}
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public function printPHP()
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{
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echo 'PHP is great.' . PHP_EOL;
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}
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}
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class bar extends foo
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{
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public function printItem($string)
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{
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echo 'Bar: ' . $string . PHP_EOL;
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}
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}
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$foo = new foo();
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$bar = new bar();
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$foo->printItem('baz'); // Output: 'Foo: baz'
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$foo->printPHP(); // Output: 'PHP is great'
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$bar->printItem('baz'); // Output: 'Bar: baz'
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$bar->printPHP(); // Output: 'PHP is great'
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?>
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]]>
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</programlisting>
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</example>
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</sect2>
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<note>
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<para>
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Unless autoloading is used, then classes must be defined before they are
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used. If a class extends another, then the parent class must be declared
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before the child class structure. This rule applies to class that inherit
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other classes and interfaces.
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</para>
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</note>
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</sect1>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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