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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>Type Hinting</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.reflection.html">Reflection</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.oop5.late-static-bindings.html">Late Static Bindings</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.typehinting" class="sect1"> <h2 class="title">Type Hinting</h2> <p class="para"> PHP 5 introduces Type Hinting. Functions are now able to force parameters to be objects (by specifying the name of the class in the function prototype) or arrays (since PHP 5.1). However, if <a href="language.types.null.html" class="type NULL">NULL</a> is used as the default parameter value, it will be allowed as an argument for any later call. </p> <div class="example"> <p><b>Example #1 Type Hinting examples</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// An example class<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">MyClass<br /></span><span style="color: #007700">{<br /> </span><span style="color: #FF8000">/**<br /> * A test function<br /> *<br /> * First parameter must be an object of type OtherClass<br /> */<br /> </span><span style="color: #007700">public function </span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #0000BB">OtherClass $otherclass</span><span style="color: #007700">) {<br /> echo </span><span style="color: #0000BB">$otherclass</span><span style="color: #007700">-></span><span style="color: #0000BB">var</span><span style="color: #007700">;<br /> }<br /><br /><br /> </span><span style="color: #FF8000">/**<br /> * Another test function<br /> *<br /> * First parameter must be an array<br /> */<br /> </span><span style="color: #007700">public function </span><span style="color: #0000BB">test_array</span><span style="color: #007700">(array </span><span style="color: #0000BB">$input_array</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$input_array</span><span style="color: #007700">);<br /> }<br />}<br /><br /></span><span style="color: #FF8000">// Another example class<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">OtherClass </span><span style="color: #007700">{<br /> public </span><span style="color: #0000BB">$var </span><span style="color: #007700">= </span><span style="color: #DD0000">'Hello World'</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> <div class="example-contents"><p> Failing to satisfy the type hint results in a catchable fatal error. </p></div> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// An instance of each class<br /></span><span style="color: #0000BB">$myclass </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyClass</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$otherclass </span><span style="color: #007700">= new </span><span style="color: #0000BB">OtherClass</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">// Fatal Error: Argument 1 must be an object of class OtherClass<br /></span><span style="color: #0000BB">$myclass</span><span style="color: #007700">-></span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #DD0000">'hello'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Fatal Error: Argument 1 must be an instance of OtherClass<br /></span><span style="color: #0000BB">$foo </span><span style="color: #007700">= new </span><span style="color: #0000BB">stdClass</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$myclass</span><span style="color: #007700">-></span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #0000BB">$foo</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Fatal Error: Argument 1 must not be null<br /></span><span style="color: #0000BB">$myclass</span><span style="color: #007700">-></span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #0000BB">null</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Works: Prints Hello World<br /></span><span style="color: #0000BB">$myclass</span><span style="color: #007700">-></span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #0000BB">$otherclass</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Fatal Error: Argument 1 must be an array<br /></span><span style="color: #0000BB">$myclass</span><span style="color: #007700">-></span><span style="color: #0000BB">test_array</span><span style="color: #007700">(</span><span style="color: #DD0000">'a string'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Works: Prints the array<br /></span><span style="color: #0000BB">$myclass</span><span style="color: #007700">-></span><span style="color: #0000BB">test_array</span><span style="color: #007700">(array(</span><span style="color: #DD0000">'a'</span><span style="color: #007700">, </span><span style="color: #DD0000">'b'</span><span style="color: #007700">, </span><span style="color: #DD0000">'c'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> <div class="example-contents"><p> Type hinting also works with functions: </p></div> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// An example class<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">MyClass </span><span style="color: #007700">{<br /> public </span><span style="color: #0000BB">$var </span><span style="color: #007700">= </span><span style="color: #DD0000">'Hello World'</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">/**<br /> * A test function<br /> *<br /> * First parameter must be an object of type MyClass<br /> */<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">MyFunction </span><span style="color: #007700">(</span><span style="color: #0000BB">MyClass $foo</span><span style="color: #007700">) {<br /> echo </span><span style="color: #0000BB">$foo</span><span style="color: #007700">-></span><span style="color: #0000BB">var</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">// Works<br /></span><span style="color: #0000BB">$myclass </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyClass</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">MyFunction</span><span style="color: #007700">(</span><span style="color: #0000BB">$myclass</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> <div class="example-contents"><p> Type hinting allowing NULL value: </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: #FF8000">/* Accepting NULL value */<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #0000BB">stdClass $obj </span><span style="color: #007700">= </span><span style="color: #0000BB">NULL</span><span style="color: #007700">) {<br /><br />}<br /><br /></span><span style="color: #0000BB">test</span><span style="color: #007700">(</span><span style="color: #0000BB">NULL</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">test</span><span style="color: #007700">(new </span><span style="color: #0000BB">stdClass</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> <p class="para"> Type Hints can only be of the <a href="language.types.object.html" class="type object">object</a> and <a href="language.types.array.html" class="type array">array</a> (since PHP 5.1) type. Traditional type hinting with <a href="language.types.integer.html" class="type int">int</a> and <a href="language.types.string.html" class="type string">string</a> isn't supported. </p> </div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="language.oop5.reflection.html">Reflection</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.oop5.late-static-bindings.html">Late Static Bindings</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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