Re: overload resolution and function pointer

From:
=?ISO-8859-1?Q?Daniel_Kr=FCgler?= <daniel.kruegler@googlemail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Mon, 14 May 2012 12:12:30 -0700 (PDT)
Message-ID:
<jorit4$68p$1@dont-email.me>
Am 11.05.2012 21:21, schrieb Marc:

Hello,

I have several overloads of a function, I have a set of arguments, and
I would like to get a function pointer to the overload the compiler
would pick if I called this function on these arguments. I am not
interested in applying the function now, I just want to get that
pointer.

Is this possible? Or is anything vaguely similar possible?


I don't know how to realize your exact need, but consider the following
as an alternative:

// Examples:
void f(int){}
void f(double){}
void f(int, bool){}

#include <utility>

template<class... Args>
struct f_caller
{
    auto operator()(Args&&... args) const ->
decltype(f(std::forward<Args>(args)...))
    {
      return f(std::forward<Args>(args)...);
    }
};

If we consider this template as a kind of "holder" for some particular
function overload f, what kind of property is missing for your use-case?

Here an example of usage:

template<class... Args>
auto test(Args&&... args) -> f_caller<Args...>
{
    return f_caller<Args...>();
}

int main(){
    test(0, true);
    test(1.2);
    test(2);
    auto f2 = test(0, 0);
    f2(0, 0);
}

There is a way of considering f2 as a function-pointer like storage of
some unknown f. We could proceed and reduce f_caller to a functor that
can be called without any arguments when we redefine it such that it
also binds the original arguments. Since I don't know what your actual
intention is, I leave that demonstration here - it might not what you
want to realize.

HTH & Greetings from Bremen,

Daniel Kr?gler

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