问题描述
人们说从
构造函数抛出异常是一种糟糕的技术;并且解决方案是创建一个函数
_create_来初始化一个对象。
复制构造函数怎么样？我们如何避免抛出异常？如果
我们已经有一个abject女巫被初始化机智_create_我们将
被迫在复制构造函数中调用create并从
中抛出异常它。
祝你有愉快的一天，
Mihai。
People say that is a bad technique to throw exception from
constructors; and that the solution would be to create a function
_create_ to initialize an object.
What about copy constructors? How can we avoid throwing exceptions? If
we already have an abject witch was initialized wit _create_ we will be
forced to call create in copy constructor and to throw exceptions from
it.
Have a nice day,
Mihai.
推荐答案
我不相信消息灵通的人说施工人员不应该扔。
他们确实说*破坏者*不应该扔掉。
构造函数抛出异常可能会导致问题，因为它b / b $ b意味着没有调用析构函数，这可能意味着必要
cleanup doesn'不会发生。
处理这个问题的标准方法是在A类中包装任何需要在其自己的类中清理的
（比方说，B，C和D类，然后制作那些类别（比如说，b，c和d）A成员的对象
。初始化
of b， c和d然后可以在A'的构造函数中出现（通过初始化
列表）。例如，如果d的初始化导致异常，则b和c
将完全构造（与A对象不同），因此将调用它们的
析构函数，即使A对象的构造函数不是。
这实现了必要的清理。
关于异常和错误处理的C ++ FAQ对此有一些有用的东西：
-
John Carson
I don''t believe that well-informed people say constructors shouldn''t throw.
They do say that *destructors* shouldn''t throw.
The throwing of an exception by a constructor can cause a problem because it
means that the destructor is not called, which may mean that necessary
cleanup doesn''t occur.
The standard way to handle this is to wrap anything in class A that needs to
be cleaned up in a class of its own (say, classes B, C and D) and then make
objects of those classes (say, b, c and d) members of A. The initialisation
of b, c and d can then occur in A''s constructor (via the initialisation
list). If, say, the initialisation of d causes an exception, then b and c
will have been fully constructed (unlike the A object) and hence their
destructors will be called, even though the A object''s constructor won''t be.
This achieves the necessary cleanup.
The C++ FAQ on Exceptions and Error Handling has some useful stuff on this:
http://www.parashift.com/c++-faq-lite/exceptions.html
--
John Carson
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