Re: D1/D2: How to check if a method has been overridden

[Max Samukha]

On 09/08/2010 12:33 AM, klickverbot wrote:


Well, I guess I should have wrote the following instead:


You can avoid messing with vtable:

class A {
    void foo( float a ) {}
    void foo( int a ) {}

    // hack to get the static address of an overload
    private static Fn funcAddr(Fn, alias fn)() {
        return cast(Fn)&fn;
    }

    private bool isOverriden(Dg, alias fn)() {
        Dg dg = &foo;
        // check if the static and dynamic addresses match
        return dg.funcptr != funcAddr!(typeof(dg.funcptr), fn);
    }

    final void bar() {

        writefln("%:", this.classinfo);
        if (isOverriden!(void delegate(float), foo))
            writefln("  foo(float) is overriden");

        if (isOverriden!(void delegate(int), foo))
            writefln("  foo(int) is overriden");
    }
}

class B : A {
   alias A.foo foo;
   override void foo( float a ) {}
}

class C : A {
   alias A.foo foo;
   override void foo( int a ) {}
}

class D : B {
   alias B.foo foo;
   override void foo( int a ) {}
}

void main()
{
    auto a = new A;
    a.bar();

    a = new B;
    a.bar();

    a = new C;
    a.bar();

    a = new D;
    a.bar();
}

No guarantees at all as you never know whether you are dealing with a 
bug or feature.