language.oop5.autoload.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Autoloading Objects</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="language.oop5.basic.html">The Basics</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.oop5.decon.html">Constructors and Destructors</a></div> <div class="up"><a href="language.oop5.html">Classes and Objects (PHP 5)</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="language.oop5.autoload" class="sect1"> <h2 class="title">Autoloading Objects</h2> <p class="para"> Many developers writing object-oriented applications create one PHP source file per-class definition. One of the biggest annoyances is having to write a long list of needed includes at the beginning of each script (one for each class). </p> <p class="para"> In PHP 5, this is no longer necessary. You may define an __autoload function which is automatically called in case you are trying to use a class/interface which hasn't been defined yet. By calling this function the scripting engine is given a last chance to load the class before PHP fails with an error. </p> <blockquote><p><b class="note">Note</b>: Exceptions thrown in __autoload function cannot be caught in the <a href="language.exceptions.html" class="link">catch</a> block and results in a fatal error. <br /> </p></blockquote> <blockquote><p><b class="note">Note</b>: Autoloading is not available if using PHP in CLI <a href="features.commandline.html" class="link">interactive mode</a>. <br /> </p></blockquote> <blockquote><p><b class="note">Note</b>: If the class name is used e.g. in <a href="function.call-user-func.html" class="function">call_user_func()</a> then it can contain some dangerous characters such as <i>../</i>. It is recommended to not use the user-input in such functions or at least verify the input in <b>__autoload()</b>. <br /> </p></blockquote> <p class="para"> <div class="example"> <p><b>Example #1 Autoload example</b></p> <div class="example-contents"><p> This example attempts to load the classes <i>MyClass1</i> and <i>MyClass2</i> from the files <var class="filename">MyClass1.php</var> and <var class="filename">MyClass2.php</var> respectively. </p></div> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">__autoload</span><span style="color: #007700">(</span><span style="color: #0000BB">$class_name</span><span style="color: #007700">) {<br /> require_once </span><span style="color: #0000BB">$class_name </span><span style="color: #007700">. </span><span style="color: #DD0000">'.php'</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">$obj </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyClass1</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">$obj2 </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyClass2</span><span style="color: #007700">(); <br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> <div class="example"> <p><b>Example #2 Autoload other example</b></p> <div class="example-contents"><p> This example attempts to load the interface <i>ITest</i>. </p></div> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /><br /></span><span style="color: #007700">function </span><span style="color: #0000BB">__autoload</span><span style="color: #007700">(</span><span style="color: #0000BB">$name</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$name</span><span style="color: #007700">);<br />}<br /><br />class </span><span style="color: #0000BB">Foo </span><span style="color: #007700">implements </span><span style="color: #0000BB">ITest </span><span style="color: #007700">{<br />}<br /><br /></span><span style="color: #FF8000">/*<br />string(5) "ITest"<br /><br />Fatal error: Interface 'ITest' not found in ...<br />*/<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> </div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="language.oop5.basic.html">The Basics</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.oop5.decon.html">Constructors and Destructors</a></div> <div class="up"><a href="language.oop5.html">Classes and Objects (PHP 5)</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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