Re: Member function pointers

[bitwise via Digitalmars-d]

On Wednesday, 9 September 2015 at 18:33:41 UTC, Prudence wrote:

On Tuesday, 27 May 2014 at 12:21:40 UTC, d coder wrote:

[...]

What's the current state of this? I'm in need of such behavior for win32 interop.

I'm thinking that one can make the above code more general by using it in a mixin and automatically generating the funcptr signature:

import std.stdio;
import std.concurrency;

extern (C) int getch();
import std.string;


template FancyDelegate(O, D)
{

const char[] FancyDelegate = "union "~O.stringof~"Delegate { "~D.stringof~" dg; struct { "~O.stringof~"* ptr; "~D.stringof.replace("delegate(", "function("~O.stringof~",").replace(",)", ")")~" funcptr; } }"; //const char[] FancyDelegate = "union "~O.stringof~"Delegate { "~D.stringof~" dg; struct { "~O.stringof~"* ptr; "~D.stringof.replace("delegate(", "function(")~" funcptr; } }";

}

class X
{
        public int z = 2;
        public void foo(int x)
        {
                //writeln(this.z*x);
                writeln(x);
        }
}

void delegate(int) dg;

mixin(FancyDelegate!(X, typeof(dg)));


void main()
{

        auto xX = new X();
        XDelegate x;
        x.dg = &xX.foo;
        
        //x.dg(3);
        x.ptr = &xX;
        x.funcptr(xX, 5);
        //x.funcptr(5);

        
        getch();
}

Unfortunately this fails when entering the function. I've tried various things(passing &xX, etc..., passing nothing(the comments, etc.)

I thought a delegate, when called, was called like a member function? It seems that a delegate is some magic black box that we can't emulate in any way shape or form due to the calling conventions used?

struct S {
        void fun() { writeln("fun" ); }
}

class C {
        void fun() { writeln("fun" ); }
}

void main(string[] args) {
        S s;
        void delegate() fn1 = &s.fun;
        fn1();

        C c = new C();
        void delegate() fn2 = &c.fun;
        fn2();

        void delegate() fn3;
        fn3.ptr = cast(void*)&s;
        fn3.funcptr = &S.fun;
        fn3();

        void delegate() fn4;
        fn4.ptr = cast(void*)c;
        fn4.funcptr = &C.fun;
        fn4();
}