How to have a function template get the parameter types of its lambda argument?

Assume we have a class template like this:

template <typename baseT, typename ...argTs> class CCallable : public baseT { public: CCallable(std::function<bool(argTs...)> lambda) : m_lambda(lambda) { } bool Invoke(argTs ...args) override { return m_lambda(args...); } private: std::function<bool(argTs...)> m_lambda; }; 

And assume we have a function template callback implemented, probably similar to this pseudo code:

template <typename baseT, typename lambdaT> CCallable<baseT, typename lambdaT::argTs...> callback(lambdaT lambda) { return CCallable<baseT, typename lambdaT::argTs...>(lambda); } 

so that we are able to do this:

auto&& functor = callback<CBase>([](int x, int y, int *sum)->bool{ *sum = x + y; return true; }); // Start passing functor around and then... int sum; functor.Invoke(7, 42, &sum); 

Please note that the parameter types of the lambda are not passed to callback as its template type arguments.

How can we implement a function template like this, to save the users from typing more codes like:

auto&& functor = callback<CBase, int, int, int*>([](int x, int y, int *sum)->bool{ *sum = x + y; return true; }); 

Thanks.

By the way, why I'm asking this is because Microsoft::WRL provides a similar template named Callback which is called many times in an opensource library I want to use. However, I prefer to build the library with GNU C++ instead of Visual C++. Therefore, it seems inevitable that I have to implement a Microsoft::WRL::Callback-like template or macro myself.