Operator overloading for lambdas?

Question

I have asked a similar question before overloading operator >> for lambdas
But i did not explained what i really wanted .

I am writing a simple wrapper around

Answer 1

What you need is a retrospective cast. A way to compose a correct function object type from passing it only a lambda (and nothing else, no template arguments, not return type specification).

A way to do it without dependencies from other libraries would be the following

#include 
#include
#include


using namespace std;


template
struct memfun_type 
{
    using type = void;
};

template
struct memfun_type
{
    using type = std::function;
};

template
typename memfun_type::type
FFL(F const &func) 
{ // Function from lambda !
    return func;
}

Then you can be aware of your lambas' return type and write the following

int main() 
{
    database_bind dbb;

    dbb >> FFL([](int i, string s) { cout << i << ' ' << s << endl; });
    dbb >> FFL([](int i) { cout << i << endl; });
    dbb >> FFL([](string s,double d) { cout << s << ' ' << d << endl; });
}