CODEWITHSUNDEEP
c++templates
Tiago Costa
Tiago Costa

Reputation: 4251

Extract function pointer arguments and return types

I'm trying to find a way to extract the type and number of arguments and return type function pointer so I can write something like this:

int foo(int x, int y)
{
    return x+y;
}

template<class T, class U>
U callfunc(T, ...);

int main()
{
    int k = callfunc(&foo, 3, 5);
}

callfunc will check if the number of arguments and the types are correct and return the result. But how should it be implemented?

I've googled a bit and found some articles covering similar topics using macros and templates but still can't do it.

Can someone provide some pointers?

Thanks!

P.S: I can't use variadic templates because VS2012 doesn't support it.

Upvotes: 2

Views: 744

Answers (1)

Ben Voigt
Ben Voigt

Reputation: 283684

You'll want some variadic templates, something like:

template<typename TResult, typename ...TArgs>
TResult callfunc(TResult (*fn)(TArgs...), TArgs... args)
{
   /* do something with the args, if you wanted */
   TResult result = fn(std::forward(args)...);
   /* do something to the return value, if you wanted */
   return std::forward(result);
}

Upvotes: 2

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