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链接</div>
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<a href="#" onmousedown="showPopup(this, 'popup00204');"><img src="seealsolink.png" border="0" alt="" title=""></a> SystemVerilog 3.1a语言参考手册</div>
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11.16 串接构造器</div>
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一个子类在实例化的时候会调用类方法<span style="color: #0000FF">new</span><span style="color: #800080">()</span>。在函数中定义的任何代码执行之前，<span style="color: #0000FF">new</span><span style="color: #800080">()</span>执行的一个动作是调用其超类的<span style="color: #0000FF">new</span><span style="color: #800080">()</span>方法，并且会沿着继承树按这种方式一直向上调用。因此，所有的构造器都会按正确的顺序调用，它们都是起始于根基类并结束于当前的类。 </p>
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如果超类的初始化方法需要参数，那么会有两种选择：一种选择是总是提供相同的参数，另外一种选择是使用super关键字。如果参数总是相同的，那么它们可以在被扩展的时候指定： </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00369"><pre class="Element12"><span style="color: #0000FF">class</span> EtherPacket <span style="color: #0000FF">extends</span> Packet<span style="color: #800080">(</span><span style="color: #FF0000">5</span><span style="color: #800080">);</span></pre></div></div>
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这个例子将<span style="color: #FF0000">5</span>传递到与<i>Packet</i>相关联的<span style="color: #0000FF">new</span>例程。 </p>
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一个更加通用的方法是使用<span style="color: #0000FF">super</span>关键字来调用超类构造器： </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00370"><pre class="Element12"><span style="color: #0000FF">function</span> <span style="color: #0000FF">new</span><span style="color: #800080">();</span>
<span style="color: #0000FF">super</span><span style="color: #800080">.</span><span style="color: #0000FF">new</span><span style="color: #800080">(</span><span style="color: #FF0000">5</span><span style="color: #800080">);</span>
<span style="color: #0000FF">endfunction</span></pre></div></div>
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为了使用这个方法，<span style="color: #0000FF">super</span><span style="color: #800080">.</span><span style="color: #0000FF">new</span><span style="color: #800080">(</span><span style="color: #FF0000">5</span><span style="color: #800080">)</span>必须是new函数执行的第一条语句。</p></div>
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