Re: NSProtocolChecker doesn't forward messages

[Kazunobu Kuriyama]

J.F.Costa wrote:

> Hi, everybody.
>
>         NSProtocolChecker instances don't forward the messages that are in
> it's protocol. Here is NSProtocolChecker's forwarding method:
>
>
> - (void) forwardInvocation: (NSInvocation*)anInvocation
> {
>  unsigned int   length;
>  void           *buffer;
>
>  if ((struct objc_method_description *)NULL
>    != [self methodDescriptionForSelector: [anInvocation selector]])
>    [[NSException exceptionWithName: NSInvalidArgumentException
>                   reason: @"Method not declared in current protocol"
>                   userInfo: nil] raise];
>
>  [anInvocation invokeWithTarget: _myTarget];
>
>  length = [[anInvocation methodSignature] methodReturnLength];
>  buffer = (void *)malloc(length);
>  [anInvocation getReturnValue: buffer];
>
>  if (0 == strcmp([[anInvocation methodSignature] methodReturnType],
>                   [[anInvocation methodSignatureForSelector:
>                                   @selector(init: )] methodReturnType]) )
>    {
>      if (((id)buffer) == _myTarget)
>         {
>           buffer = self;
>           [anInvocation setReturnValue: buffer];
>         }
>    }
>
>  return;
> }
>
>         Notice that the comparison symbol in the protocol check is wrong, it
> should be '=='. Besides that, there is something wrong with the
> condition in the second 'if', because the former segfaults. What is
> the correct condition?
In addition to the issues above, there's a memory leak.

BTW, when should we use objc_malloc() instead of malloc()?  Is there any 
plan
to make objc_malloc() better than malloc()?

Thanks,
- Kazunobu Kuriyama