Re: interface and class inheritance

[Ali Çehreli]

On 11/14/2013 01:20 PM, Oleg B wrote:
[code]
import std.stdio;
interface A { void funcA(); }
class B { final void funcA() { writeln( "B.funcA()" ); } }

class C: B, A { }

void main()
{
     auto c = new C;
     c.funcA();
}
[code/]

$ dmd -run interface.d
interface.d(6): Error: class interface.C interface function 'void
funcA()' is not implemented

if swap A and B
[code]
class C: A, B { }
[code/]

$ dmd -run interface.d
interface.d(6): Error: class interface.C base type must be interface,
not interface.B

how to workaround this without change in class B and interface A?

One way is to expose B through 'alias this' (not by inheritance) but it 
doesn't scale because currently only one 'alias this' is allowed.

import std.stdio;

interface A { void funcA(); }
class B { final void funcA() { writeln( "B.funcA()" ); } }

class C: A {
    B b;
    alias b this;

    this(){
        b = new B();
    }

    void funcA()
    {
        return b.funcA();
    }
}

void main()
{
    auto c = new C;
    c.funcA();
}

Ali