warning ... is hidden in ...

[Derek Parnell]

On Sat, 03 May 2008 11:43:59 +0200, Frits van Bommel wrote:

>>> "Derek Parnell" <derek at psych.ward> wrote in message 
>>> news:1pg84i0mr3ihw$.1ng68jjvixchm$.dlg at 40tude.net...
>>>> Using dmd 2.013 I'm now getting some messages along the lines of ...
>>>>
>>>>  warning: class Foo Object opCmp is hidden in Foo
>>>>
>>>> What does this actually mean and how can I remove the warning (without
>>>> removing the -w switch)?

 
> Presumably your code currently looks something like:
> ---
> class C {
>      int opCmp(C c) {
>          // implementation
>      }
> }

Yes it does.


> ---
> If you want to get rid of the warning, try one of these:
> ---
> class C {
>      /// Overrides Object.opCmp, throws if the argument is not a C.
>      override int opCmp(Object o) {
>          if (C c = cast(C) o)
>              return opCmp(c);
>          throw new Exception("Can't compare C to " ~ o.classinfo.name);
>      }
>      int opCmp(C c) {
>          // implementation
>      }
> }
> ---
> or
> ---
> class C {
>      override int opCmp(Object o) {
>          if (C c = cast(C) o) {
> 	    // implementation
>          }
>          throw new Exception("Can't compare C to " ~ o.classinfo.name);
>      }
> }
> ---
> The second one is essentially the inlined version of the first, but will 
> be less efficient when the a and b in "a < b" are statically known to be 
> instances of C.
> And both versions assume the argument isn't null; if you want to handle 
> null input (not sure why you would) you'll need some more checking.

OMG!!!

Firstly, this actually works! 

Secondly, WTF!!!  And how exactly is this making coding easier for people? 

It would seem that every bloody time anyone codes a method that just
happens to be defined in Object, you need to go through this syntactially
hurdle to do something that seems so commonly required. For example, I also
coded 'toString' in my class, which meant that I have to now ALSO code this
waste of space ...

     override string toString(){ return this.toString();}

This seems to be madness to me. What is it that I just not getting?

I want coding to be as easy as possible which means that I expect the
compiler to do the tedious work for me. Am I expecting too much? I mean, if
I code in MY class a method called "toString()" why does the compiler
bother to assume that I'm somehow referring to the method in Object? 

-- 
Derek Parnell
Melbourne, Australia
skype: derek.j.parnell