Re: map value as function pointer

From:

"mlimber" <mlimber@gmail.com>

Newsgroups:

comp.lang.c++

Date:

16 May 2006 14:58:57 -0700

Message-ID:

<1147816736.990390.144070@38g2000cwa.googlegroups.com>

Please don't top-post.

Darwin Lalo wrote:

like this:

struct GEvent
{
    virtual void invoke() = 0;
    virtual ~GEvent(){
    };
};

template <class T>
struct GInvokeHandler : public GEvent{
    T* p;
    void (T::*pmfn) ();
    GInvokeHandler(T *_p, void ( T::*_pmfn) ()){
        p = _p;
        pmfn = _pmfn;
    }

See http://www.parashift.com/c++-faq-lite/ctors.html#faq-10.6.

    void invoke()
    {
        return (p->*pmfn) ();
    }
};

long foo(T *p, void (T::*pmfn)()){
    GEvent* pEvent = new GInvokeHandler<T>(p,pmfn);
    map<long, GEvent*> _map;
    ...
}

This is basically the same as using a functor to call a member function
as mentioned previously on this thread, and, as also previously
mentioned, it would work fine *if* the user can supply the object
instance on which to invoke the member function when building the map.
If not, it must be done with static members or non-member functions.
(This disclaimer also assumes that the "different" classes mentioned in
the OP cannot be manipulated through static or dynamic polymorphism.)

Cheers! --M