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<h3><span lang=EN-US>68. </span><span style='font-family:宋体;mso-ascii-font-family:
Arial;mso-hansi-font-family:Arial'>大量使用断言来说明内部的假设和不变性</span></h3>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><b style='mso-bidi-font-weight:normal'><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>摘要</span></b></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>要善于使用断言！大量地使用</span><span lang=EN-US>assert</span><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>或它的等价物来说明模块内部（即调用方和被调用方由同一人或小组维护）的各种假设，这些假设必须成立，否则的话就说明出现了编程错误（例如：函数的调用方检测到该函数的后置条件不成立）（参见第</span><span
lang=EN-US>70</span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>条）。同时要确保断言不会产生副作用。</span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><b style='mso-bidi-font-weight:normal'><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>讨论</span></b></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal style='margin-left:36.0pt'><i style='mso-bidi-font-style:
normal'><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>错误在你查找它们的时候是很难被发现的，而如果你已经假定了代码中没有错误，那么就更难发现它们了。</span></i><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>——</span><span lang=EN-US>Steve McConnell</span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>断言的价值从来不会被高估。</span><span lang=EN-US>assert</span><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>宏和它在编译期的等价物断言模板是在开发过程中用来检测和调试编程错误的非常重要的工具。在众多此类工具之中，它们的复杂度</span><span
lang=EN-US>/</span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>有效性之比可能是最高的。项目的成功与否会部分地取决于开发人员有没有在代码中有效地使用断言。</span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
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