Re: Conversion of pointer-to-member

Hi!

Frank Birbacher schrieb:


My new approach is another level of indirection (which is known to solve
most problems ;) ). I used a new "Test" member which just points to the
object I want and then I use a pointer-to-member to just this pointer
(VARIANT 1). But that is not the way to go.

Well, the way I prefer is using a boost::function object which resolves
the object I want. I pass a Test object as an argument and get back the
Base object I want. (VARIANT 2)

#include <iostream>
#include <ostream>
#include <boost/function.hpp>
#include <boost/bind.hpp>

struct Base {
    virtual void doBar() =0;
};

template<typename T>
struct Dev : Base {
    Dev(T t) : t(t) {}
    void doBar() { std::cout << t << '\n'; }
    const T t;
};

struct Test {
    Dev<int> i;
    Base* const bi;

    Dev<float> f;
    Base* const bf;

    Test()
        : i(8)
        , bi(&i)
        , f(2.3)
        , bf(&f)
    {}
};

int main()
{
    //VARIANT 1
    Base* const Test::* const p = &Test::bi;
    Test t;
    (t.*p)->doBar();

    //VARIANT 2, preferred
    boost::function1<Base&, Test&> const p2(
boost::bind<Base&>(&Test::f,
_1) );
    p2(t).doBar();
}

It just seems to me the boost::function is a bit of overkill to such a
little thing which isn't far away from regular pointer-to-members.

Frank

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