Re: Call different member functions on object sequence with a generic handler function?

[Timoses via Digitalmars-d-learn]

On Friday, 29 June 2018 at 16:44:36 UTC, Robert M. Münch wrote:
I hope this is understandable... I have:
class C {
        void A();
        void B();
        void C();
}

I'm iterating over a set of objects of class C like:

foreach(obj; my_selected_objs){
        ...
}

The iteration and code before/afterwards always looks the same, 
I need this iteration for many of the memember functions like 
C.A() and C.B(), etc.

foreach(obj; my_selected_objs){
        ...
        obj.A|B|C()
        ...
}

So, how can I write a generic handler that does the iteration, 
where I can specify which member function to call?

void do_A() {
        handler(C.A()); ???
}

void do_B() {
        handler(C.B()); ???
}

handler(???){
        foreach(obj: my_selected_objs){
                ???
        }
}

Viele Grüsse.

Trying to fiddle around a bit with delegates.. But why is the 
context for delegates not working for classes??

https://run.dlang.io/is/Rxeukg

    import std.stdio;

    class Aclass
    {
        int i;
        void foo() { writeln("called ", i); }
    }
    struct Bstruct
    {
        int i;
        void foo() { writeln("called ", i); }
    }


    template callFoo(T)
    {
        alias Dun = void delegate();

        void callFoo(T t)
        {
            Dun fun;
            fun.funcptr = &T.foo;
            fun.ptr = cast(void*)(&t);

            Dun gun;
            gun = &t.foo;

            writeln(fun.ptr, " (fun.ptr of " ~ T.stringof ~ ")");
            writeln(gun.ptr, " (gun.ptr of " ~ T.stringof ~ ")");
            writeln(&t, " (Address of instance (context))");

            fun();
            gun();
        }

    }

    void main()
    {
        auto a = new Aclass();
        a.i = 5;
        auto b = Bstruct();
        b.i = 7;
        writeln("---- Doesn't work ----");
        callFoo(a);
        writeln("\n---- Works ----");
        callFoo(b);
    }