Curiously recurring template pattern: Difference between revisions

Revision as of 12:27, 20 June 2006

Revision as of 07:34, 6 July 2006

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}

};

struct derived : base<derived>

{

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To be more explicit about the above example, let us consider the case where we have a base class with '''no virtual functions'''. Whenever the base class calls another member function, it will always call it's own base class functions. When we inherit from this class, a derived class, we inherit all the member variables and member functions that weren't overridden (no constructors or destructors, of course, either). If the derived class calls an inherited function that then calls another member function, it will never call any derived member functions. As a result of this behaviour, most C++ programmers define member functions as virtual to avoid this problem.

However, if base class member functions use the CRTP pattern for all member function calls, the overridenoverridden functions in the derived class will get selected at compile time. This effectively emulates the virtual function call system without the costs in size or function call overhead (VTBL structures, and method lookups, multiple-inheritance VTBL machinery).

==See also==