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php-manual-zh-5.2.4-1mdv2008.1.noarch.rpm

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>PHP 手册</TH
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>章 19. 类与对象（PHP 5）</TD
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>Type Hinting</A
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><P
>&#13;   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).
  </P
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>例 19-41. Type Hinting examples</B
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><code><font color="#000000">
<font color="#0000BB">&lt;?php<br /></font><font color="#FF8000">// An example class<br /></font><font color="#007700">class </font><font color="#0000BB">MyClass<br /></font><font color="#007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;</font><font color="#FF8000">/**<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;* A test function<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;* First parameter must be an object of type OtherClass<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*/<br />&nbsp;&nbsp;&nbsp;&nbsp;</font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">test</font><font color="#007700">(</font><font color="#0000BB">OtherClass $otherclass</font><font color="#007700">) {<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;echo </font><font color="#0000BB">$otherclass</font><font color="#007700">-&gt;</font><font color="#0000BB">var</font><font color="#007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br /><br /><br />&nbsp;&nbsp;&nbsp;&nbsp;</font><font color="#FF8000">/**<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;* Another test function<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;* First parameter must be an array<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*/<br />&nbsp;&nbsp;&nbsp;&nbsp;</font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">test_array</font><font color="#007700">(array </font><font color="#0000BB">$input_array</font><font color="#007700">) {<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</font><font color="#0000BB">print_r</font><font color="#007700">(</font><font color="#0000BB">$input_array</font><font color="#007700">);<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />}<br /><br /></font><font color="#FF8000">// Another example class<br /></font><font color="#007700">class </font><font color="#0000BB">OtherClass </font><font color="#007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;</font><font color="#0000BB">public $var </font><font color="#007700">= </font><font color="#DD0000">'Hello World'</font><font color="#007700">;<br />}<br /></font><font color="#0000BB">?&gt;</font>
</font>
</code></TD
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><P
>&#13;    Failing to satisfy the type hint results in a fatal error.
   </P
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><code><font color="#000000">
<font color="#0000BB">&lt;?php<br /></font><font color="#FF8000">// An instance of each class<br /></font><font color="#0000BB">$myclass </font><font color="#007700">= new </font><font color="#0000BB">MyClass</font><font color="#007700">;<br /></font><font color="#0000BB">$otherclass </font><font color="#007700">= new </font><font color="#0000BB">OtherClass</font><font color="#007700">;<br /><br /></font><font color="#FF8000">// Fatal Error: Argument 1 must be an object of class OtherClass<br /></font><font color="#0000BB">$myclass</font><font color="#007700">-&gt;</font><font color="#0000BB">test</font><font color="#007700">(</font><font color="#DD0000">'hello'</font><font color="#007700">);<br /><br /></font><font color="#FF8000">// Fatal Error: Argument 1 must be an instance of OtherClass<br /></font><font color="#0000BB">$foo </font><font color="#007700">= new </font><font color="#0000BB">stdClass</font><font color="#007700">;<br /></font><font color="#0000BB">$myclass</font><font color="#007700">-&gt;</font><font color="#0000BB">test</font><font color="#007700">(</font><font color="#0000BB">$foo</font><font color="#007700">);<br /><br /></font><font color="#FF8000">// Fatal Error: Argument 1 must not be null<br /></font><font color="#0000BB">$myclass</font><font color="#007700">-&gt;</font><font color="#0000BB">test</font><font color="#007700">(</font><font color="#0000BB">null</font><font color="#007700">);<br /><br /></font><font color="#FF8000">// Works: Prints Hello World<br /></font><font color="#0000BB">$myclass</font><font color="#007700">-&gt;</font><font color="#0000BB">test</font><font color="#007700">(</font><font color="#0000BB">$otherclass</font><font color="#007700">);<br /><br /></font><font color="#FF8000">// Fatal Error: Argument 1 must be an array<br /></font><font color="#0000BB">$myclass</font><font color="#007700">-&gt;</font><font color="#0000BB">test_array</font><font color="#007700">(</font><font color="#DD0000">'a string'</font><font color="#007700">);<br /><br /></font><font color="#FF8000">// Works: Prints the array<br /></font><font color="#0000BB">$myclass</font><font color="#007700">-&gt;</font><font color="#0000BB">test_array</font><font color="#007700">(array(</font><font color="#DD0000">'a'</font><font color="#007700">, </font><font color="#DD0000">'b'</font><font color="#007700">, </font><font color="#DD0000">'c'</font><font color="#007700">));<br /></font><font color="#0000BB">?&gt;</font>
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</code></TD
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>&#13;    Type hinting also works with functions:
   </P
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><code><font color="#000000">
<font color="#0000BB">&lt;?php<br /></font><font color="#FF8000">// An example class<br /></font><font color="#007700">class </font><font color="#0000BB">MyClass </font><font color="#007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;</font><font color="#0000BB">public $var </font><font color="#007700">= </font><font color="#DD0000">'Hello World'</font><font color="#007700">;<br />}<br /><br /></font><font color="#FF8000">/**<br /> * A test function<br /> *<br /> * First parameter must be an object of type MyClass<br /> */<br /></font><font color="#007700">function </font><font color="#0000BB">MyFunction </font><font color="#007700">(</font><font color="#0000BB">MyClass $foo</font><font color="#007700">) {<br />&nbsp;&nbsp;&nbsp;&nbsp;echo </font><font color="#0000BB">$foo</font><font color="#007700">-&gt;</font><font color="#0000BB">var</font><font color="#007700">;<br />}<br /><br /></font><font color="#FF8000">// Works<br /></font><font color="#0000BB">$myclass </font><font color="#007700">= new </font><font color="#0000BB">MyClass</font><font color="#007700">;<br /></font><font color="#0000BB">MyFunction</font><font color="#007700">(</font><font color="#0000BB">$myclass</font><font color="#007700">);<br /></font><font color="#0000BB">?&gt;</font>
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>&#13;   Type Hints can only be of the <A
HREF="language.types.object.html"
><B
CLASS="type"
>object</B
></A
> and <A
HREF="language.types.array.html"
><B
CLASS="type"
>array</B
></A
>
   (since PHP 5.1) type. Traditional type hinting with <A
HREF="language.types.integer.html"
><B
CLASS="type"
>int</B
></A
> and
   <A
HREF="language.types.string.html"
><B
CLASS="type"
>string</B
></A
> isn't supported.
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