Re: how to make new C return other static type than C

[deed]

Thanks for your replies. How about this:

interface I {}
interface I1 : I
{
    void setx(int x);
    int getx();
    int getSum();
}

interface I2 : I
{
    void sety(int y);
    int gety();
    int getSum();
}

class Impl : I1, I2
{
    int x, y;

    void setx(int x)   { this.x = x;   }
    int getx()         { return x;     }
    void sety(int y)   { this.y = y;   }
    int gety()         { return y;     }
    int getSum()       { return x + y; }
}

class C
{
    I1 i1;
    I2 i2;
    I currentInterface;

    this()
    {
        i1 = new Impl;    // static type I1
        i2 = csat(I2)i1;  // try to refer to same object through 
i2
        currentInterface = i1;
    }

    void switchInterface()   // Could be private and called 
depending on
                             // internal state
    {
        if (currentInterface == i1) { currentInterface = i2; }
        else                        { currentInterface = i1; }
    }

    /* Direct all method calls to the current interface...
       Perhaps opDispatch?
    */
}

void main()
{
    auto c = new C;
    c.setx(5);       // Should set x to 5 through i1
    c.getSum();      // Should return 5. (5 + 0)
    c.sety(3);       // Should not be possible
    c.switchInterface()   // currentInterface is now i2
    c.setx(10);      // Should not be possible
    c.sety(3);       // Should set y to 8 through i2
    c.getSum();      // Should return 8. (5 + 3)
}


- Could this be possible?
- Will i1 and i2 expose different interfaces to the same object?
- How can a method call on an object be directed to an internal 
object/interface?