Initialize global array of function pointers at either compile-time, or run-time before main()

Question

I\'m trying to initialize a global array of function pointers at compile-time, in either C or C++. Something like this:

module.h

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Answer 1

I was going to suggest this question is more about C, but on second thoughts, what you want is a global container of function pointers, and to register available functions into it. I believe this is called a Singleton (shudder).

You could make myfunc_array a vector, or wrap up a C equivalent, and provide a function to push myfuncs into it. Now finally, you can create a class (again you can do this in C), that takes a myfunc and pushes it into the global array. This will all occur immediately prior to main being called. Here are some code snippets to get you thinking:

// a header

extern vector myfunc_array;

struct _register_myfunc { 
    _register_myfunc(myfunc lolz0rs) {
        myfunc_array.push_back(lolz0rs);
    }
}

#define register_myfunc(lolz0rs) static _register_myfunc _unique_name(lolz0rs);

// a source

vector myfunc_array;

// another source

int16_t myfunc_1() { ... }
register_myfunc(myfunc_1);

// another source

int16_t myfunc_2() { ... }
register_myfunc(myfunc_2);

Keep in mind the following:

• You can control the order the functions are registered by manipulating your link step.
• The initialization of your translation unit-scoped variables occurs before main is called, i.e. the registering will be completed.
• You can generate unique names using some macro magic and __COUNTER__. There may be other sneaky ways that I don't know about. See these useful questions:
  • Unnamed parameters in C
  • Unexpected predefined macro behaviour when pasting tokens
  • How to generate random variable names in C++ using macros?