C++ cannot initialize static data member [duplicate]

The following declaration within a definition of your class is not enough:

private:
    static map_type * map;

In one .cpp file, you must also add:

map_type* BaseFactory::map = NULL;

This article might help you too: Static data members (C++ only)
+ this question, which has almost 100k views by now: Initializing private static members

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