delegate bug?

[Jacob Carlborg]

On 2012-11-09 14:36, Jack Applegame wrote:
> This code:
>
> import std.stdio;
> class A {
>    void func() { writeln("A"); }
> }
> class B : A {
>    override void func() { writeln("B"); }
> }
> void main() {
>    A a = new A;
>    B b = new B;
>
>    auto dg = &a.func;
>    dg();
>
>    dg.ptr = cast(void*)b;
>    dg();
> }
>
> outputs:
> A
> A
>
> but expected:
> A
> B

This is expected behavior. Delegates do not perform any dynamic 
dispatch. The method that is called is chosen when the delegate is 
created, i.e. "auto dg = &a.func;"

You can workaround this by calling another method in "A" that will call 
the actual method you want to call, something like this:

class A
{
     void resolveVirtualCall ()
     {
         func();
     }
}

auto dg = &a.resolveVirtualCall;

-- 
/Jacob Carlborg