DRAFT document on coding conventions in kde libraries

[Leo Savernik]

Am Dienstag, 7. März 2006 09:39 schrieb Thiago Macieira:
[...]
> No, I meant complex covariant return values:
>
> struct A {
>   int i;
>   virtual ~A();
>   virtual A *f() { return new A(); }
> };
>
> struct A2 {
>   int j;
>   virtual ~A2();
> };
>
> struct B: public A2, public A
> {
>   virtual B* f() { return new B(); }
> };
>
> gcc 2.95 can't compile this. If you do:
>   B *b = new B;
>   A *a = b;
>
> Then a == b, but not in value (the pointer values differ).

Augmenting the snippet so that it builds:
struct A {
  int i;
  virtual ~A() {}
  virtual A *f() { return new A(); }
};

struct A2 {
  int j;
  virtual ~A2() {}
};

struct B: public A2, public A
{
  virtual B* f() { return new B(); }
};

#include <stdio.h>
int main() {
  B *b = new B;
  A *a = b;
  printf("a: %p b: %p a==b: %d\n", a, b, a == b);
}


Compiled with gcc-2.95.2 (yes, really old version!) results in:
a: 0x8049fb8 b: 0x8049fb0 a==b: 1

So I can't follow your concern. Whatever, msvc6 doesn't even compile this.

mfg
	Leo