描述:
COM类初始化时问题,在FinalConstruct与构造函数中初始化有何区别,是否如果在构造函数中有成员函数调用必须使用FinalConstruct
解决方案1:
深入解析ATL里这段说的很明白,
解决方案2: There are advantages to performing initialization in FinalConstruct rather than the constructor of your class:
You cannot return a status code from a constructor, but you can return an HRESULT by means of FinalConstruct's return value. When objects of your class are being created using the standard class factory provided by ATL, this return value is propagated back to the COM client allowing you to provide them with detailed error information.
You cannot call virtual functions through the virtual function mechanism from the constructor of a class. Calling a virtual function from the constructor of a class results in a statically resolved call to the function as it is defined at that point in the inheritance hierarchy. Calls to pure virtual functions result in linker errors.
Your class is not the most derived class in the inheritance hierarchy — it relies on a derived class supplied by ATL to provide some of its functionality. There is a good chance that your initialization will need to use the features provided by that class (this is certainly true when objects of your class need to aggregate other objects), but the constructor in your class has no way to access those features. The construction code for your class is executed before the most derived class is fully constructed.
However, FinalConstruct is called immediately after the most derived class is fully constructed allowing you to call virtual functions and use the reference-counting implementation provided by ATL.
----From MSDN
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