C++ Template deduction while calling a template function

Question

FastDelegate refers to http://www.codeproject.com/KB/cpp/FastDelegate.aspx, but I don't think it is related.

I have code like following, and got error.

#include <FastDelegate.h>


using namespace fastdelegate;

template <typename T>
T Getter() {}

template <typename T>
void Setter(T) {}

template <typename T>
class Prop
{
public:
    typedef FastDelegate0<T> Getter;
    typedef FastDelegate1<T> Setter;

    Prop(Getter getter, Setter setter) :
        m_Getter(getter), m_Setter(setter)
    {

    }

private:
    Getter m_Getter;
    Setter m_Setter;
};

template <typename T>
inline Prop<T>* MakeProp(FastDelegate0<T> getter, FastDelegate1<T> setter)
{
    return new Prop<T>(getter, setter);
}

static int Target = 0;
int main()
{
    FastDelegate0<int> fdGetter(Getter<int>);
    Prop<int>* c = MakeProp(fdGetter, Setter<int>);
    // ^^^^ error: no matching function for call to 'MakeProp'
}

If changed the main() to:

int main()
{
    FastDelegate0<int> fdGetter(Getter<int>);
    FastDelegate1<int> fdSetter(Setter<int>);
    Prop<int>* c = MakeProp(fdGetter, fdSetter); // It works.
}

or:

int main()
{
    FastDelegate0<int> fdGetter(Getter<int>);
    Prop<int>* c = MakeProp<int>(fdGetter, Setter<int>); // It works, too.
}

I think, MakeProp() should get the T from fdGetter (which is int, than called the contructor of FastDelegate1<int> automatically. But it did not. Why?

P.S. I would like to save the getter and setter in Prop, any suggestion for this approach is welcome. Maybe it is bad to copy the instance of FastDelegate* during passing arguments in function.

Answer 1

Have you tried

Prop<int>* c = MakeProp(FastDelegate0<int>(Getter<int>), FastDelegate1<int>(Setter<int>));

?

Setter<int> cannot be converted to FastDelegate1<T>!