Why these code is valid:

class A {
  public char[] test() {
    return "A";
  }
}

class B : A {
}

class C : B {
  public char[] test() {
    return super.test() ~ " C";
  }
}

But these are not?

class A {
  public char[] test() {
    return "A";
  }
}

class B : A {
  public void test(char[] a) {
  }
}

class C : B {
  public char[] test() {
    return super.test() ~ " C";
  }
}

Does this help?

Eric Suen schrieb:
> 
> class A {
>   public char[] test() {
>     return "A";
>   }
> }
> 
> class B : A {
    alias A.test test;
>   public void test(char[] a) {
>   }
> }
> 
> class C : B {
>   public char[] test() {
>     return super.test() ~ " C";
>   }
> }

Is this the bug of D compiler or the feature of
D language? this will be a big problem for visitor pattern,
for examples, Parser, like:

visit(IfStatement s);
visit(WhileStatement s);
....

So if I want override some of the method, how? that is really weird, Java doesn't has this problem...

Eric

"Frank Benoit" <keinfarbton@googlemail.com>
> Does this help?
>
> Eric Suen schrieb:
>>
>> class A {
>>   public char[] test() {
>>     return "A";
>>   }
>> }
>>
>> class B : A {
>    alias A.test test;
>>   public void test(char[] a) {
>>   }
>> }
>>
>> class C : B {
>>   public char[] test() {
>>     return super.test() ~ " C";
>>   }
>> }

Yes, it is not bug it is a feature. :(

From http://www.digitalmars.com/d/1.0/function.html
"However, when doing overload resolution, the functions in the base
class are not considered:"
"To consider the base class's functions in the overload resolution
process, use an AliasDeclaration:"

Also see my postings "override and overload" 13-Nov-06
and "aliasing base methods" from 25-Feb-07


Eric Suen schrieb:
> Is this the bug of D compiler or the feature of
> D language? this will be a big problem for visitor pattern,
> for examples, Parser, like:
> 
> visit(IfStatement s);
> visit(WhileStatement s);
> .....
> 
> So if I want override some of the method, how? that is really weird, Java doesn't has this problem...
> 
> Eric
> 
> "Frank Benoit" <keinfarbton@googlemail.com>
>> Does this help?
>>
>> Eric Suen schrieb:
>>> class A {
>>>   public char[] test() {
>>>     return "A";
>>>   }
>>> }
>>>
>>> class B : A {
>>    alias A.test test;
>>>   public void test(char[] a) {
>>>   }
>>> }
>>>
>>> class C : B {
>>>   public char[] test() {
>>>     return super.test() ~ " C";
>>>   }
>>> }
> 
>