August 2021
Intermediate to advanced
450 pages
9h 36m
Chinese
Content preview from C++程序设计：原理与实践（基础篇）（原书第2版）
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5.5.2 被调用者处理错误
在framed_area（）内部实现错误检查非常简单，error（）仍然可以被用于错误报告：
这一实现非常好，而且我们也不用为每一个frame_area（）调用写一个测试。在一个大程序中，对一个会被调用500次的常用函数来说，这一点非常有用。而且，如果需要对错误处理进行修改的话，我们只需要在一处地方进行改动就可以了。
需要注意的是，在这里我们很自然地从“调用者必须检查参数”的方法转变到“函数必须检查自己的参数”的方法（也称为“被调用者检查”）。后者的好处在于参数检查只在一个地方实现。我们不需要在整个程序中查找调用点。而且，参数检查只在这一个地方实现，我们可以方便地掌握参数检查的全部信息。
让我们把这一思想应用于area（）中：
上面程序实现了对于area（）调用的所有错误处理。因此我们不再需要调用framed_area（）。进一步改进，我们可能需要对于错误信息的更准确描述。
函数的参数检查看上去很简单，但是为什么人们不总这么做呢？不注意错误处理是一个原因，粗心大意是另一个原因。此外，还有许多其他因素： ...
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