Implement abstract class as a local class? pros and cons
c++, class, local
Solution
You could define `B` in the unnamed namespace of the implementation file where you implement `GetPtrToAImplementation()`.
`A` should have a virtual dtor.
By the current C++ standard, you cannot use local classes as template arguments. (Which means you can't use them with the STL, for example.)
Problem
for some reason I'm thinking on implementing interface within a some function(method) as local class. Consider following: ``` class A{ public: virtual void MethodToOverride() = 0; }; A * GetPtrToAImplementation(){ class B : public A { public: B(){} ~B(){} void MethodToOverride() { //do something } }; return static_cast<A *>(new B()); } int _tmain(int argc, _TCHAR* argv[]) { A * aInst = GetPtrToAImplementation(); aInst->MethodToOverride(); delete aInst; return 0; } ``` the reasons why I'm doing this are: - I'm lazy to implement class (B) in separate files - MethodToOverride just delegates call to other class - Class B shouldn't be visible to other users - no need to worry about deleting aInst since smart pointers are used in real implementation So my question is if I'm doing this right? Thanks in advance!