c++0x: overloading on lambda arity

Question

I\'m trying to create a function which can be called with a lambda that takes either 0, 1 or 2 arguments. Since I need the code to work on both g++ 4.5 and vs2010(which doe

Answer 1

A lambda function is a class type with a single function call operator. You can thus detect the arity of that function call operator by taking its address and using overload resolution to select which function to call:

#include 

template
void do_stuff(F& f,R (F::*mf)() const)
{
    (f.*mf)();
}

template
void do_stuff(F& f,R (F::*mf)(A1) const)
{
    (f.*mf)(99);
}

template
void do_stuff(F& f,R (F::*mf)(A1,A2) const)
{
    (f.*mf)(42,123);
}

template
void do_stuff(F f)
{
    do_stuff(f,&F::operator());
}

int main()
{
    do_stuff([]{std::cout<<"no args"<

Be careful though: this won't work with function types, or class types that have more than one function call operator, or non-const function call operators.