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>章 19. 类与对象（PHP 5）</TD
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>Object Interfaces</A
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><P
> Object interfaces allow you to create code which specifies which methods a
class must implement, without having to define how these methods are
handled.
</P
><P
> Interfaces are defined using the interface keyword, in the same way as a
standard class, but without any of the methods having their contents
defined.
</P
><P
> All methods declared in an interface must be public, this is the nature of an
interface.
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><TT
CLASS="literal"
>implements</TT
></A
></H2
><P
> To implement an interface, the <TT
CLASS="literal"
>implements</TT
> operator is used.
All methods in the interface must be implemented within a class; failure to do
so will result in a fatal error. Classes may implement more than one interface
if desired by separating each interface with a comma.
</P
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><B
>注意: </B
>
A class cannot implement two interfaces that share function names, since
it would cause ambiguity.
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>范例</A
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>例 19-19. Interface example</B
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><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#FF8000">// Declare the interface 'iTemplate'<br /></font><font color="#0000BB">interface iTemplate<br /></font><font color="#007700">{<br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">setVariable</font><font color="#007700">(</font><font color="#0000BB">$name</font><font color="#007700">, </font><font color="#0000BB">$var</font><font color="#007700">);<br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">getHtml</font><font color="#007700">(</font><font color="#0000BB">$template</font><font color="#007700">);<br />}<br /><br /></font><font color="#FF8000">// Implement the interface<br />// This will work<br /></font><font color="#007700">class </font><font color="#0000BB">Template implements iTemplate<br /></font><font color="#007700">{<br /> </font><font color="#0000BB">private $vars </font><font color="#007700">= array();<br /> <br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">setVariable</font><font color="#007700">(</font><font color="#0000BB">$name</font><font color="#007700">, </font><font color="#0000BB">$var</font><font color="#007700">)<br /> {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">vars</font><font color="#007700">[</font><font color="#0000BB">$name</font><font color="#007700">] = </font><font color="#0000BB">$var</font><font color="#007700">;<br /> }<br /> <br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">getHtml</font><font color="#007700">(</font><font color="#0000BB">$template</font><font color="#007700">)<br /> {<br /> foreach(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">vars </font><font color="#007700">as </font><font color="#0000BB">$name </font><font color="#007700">=> </font><font color="#0000BB">$value</font><font color="#007700">) {<br /> </font><font color="#0000BB">$template </font><font color="#007700">= </font><font color="#0000BB">str_replace</font><font color="#007700">(</font><font color="#DD0000">'{' </font><font color="#007700">. </font><font color="#0000BB">$name </font><font color="#007700">. </font><font color="#DD0000">'}'</font><font color="#007700">, </font><font color="#0000BB">$value</font><font color="#007700">, </font><font color="#0000BB">$template</font><font color="#007700">);<br /> }<br /> <br /> return </font><font color="#0000BB">$template</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#FF8000">// This will not work<br />// Fatal error: Class BadTemplate contains 1 abstract methods<br />// and must therefore be declared abstract (iTemplate::getHtml)<br /></font><font color="#007700">class </font><font color="#0000BB">BadTemplate implements iTemplate<br /></font><font color="#007700">{<br /> </font><font color="#0000BB">private $vars </font><font color="#007700">= array();<br /> <br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">setVariable</font><font color="#007700">(</font><font color="#0000BB">$name</font><font color="#007700">, </font><font color="#0000BB">$var</font><font color="#007700">)<br /> {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">vars</font><font color="#007700">[</font><font color="#0000BB">$name</font><font color="#007700">] = </font><font color="#0000BB">$var</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#0000BB">?></font>
</font>
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><P
> See also the <A
HREF="language.operators.type.html"
>instanceof</A
>
operator.
</P
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