Re: [objc-improvements] Warnings when compiling GNUStep

[Ziemowit Laski]

On Thursday, Sep 4, 2003, at 02:07 US/Pacific, Nicola Pero wrote:

> > > but since Objective-C allows multiple root classes, the compiler
> > > cannot statically decide to focus on NSObject.
> > > What should we do?  I see 3 choices:
> > >    (1) Leave things as they are.  Users will be able to suppress the
> > > above warning by
> > >        casting the receiver to the root class (in above case, 
> > > '(NSObject
> > > *)').
> > >    (2) Build a list of all plausible root classes (i.e., classes 
> > > without
> > > superclasses),
> > >        and consult all instance methods for those classes when
> > > dispatching messages to
> > >        'Class'
> > >    (3) Treat messages to 'Class' the same way we treat messages to 
> > > 'id',
> > > i.e., consult
> > >        all class and instance methods available.  This is what the
> > > compiler appears to
> > >        have done until now (in its mercurial and buggy way).
> >
> > I've implemented 2. in my patch, and I think this is correct and
> > consistent with the intention of the current behavior.
>
> I agree.  That is what should happen.  When looking up methods of a
> receiver of type 'Class', an instance method of a non-root class should
> not be found (big warning!); an instance method of a root class should 
> be
> found (no warning if only one is found, warning if conflicting methods 
> are
> found).  I think this is correct because this is how messaging works.

Yes, I've come around on this issue also. :-)  So long as the 
implementation
is efficient (and I too now realize there's no reason why it couldn't 
be),
we should look among root class instance methods as a last resort.

--Zem
--------------------------------------------------------------
Ziemowit Laski                 1 Infinite Loop, MS 301-2K
Mac OS X Compiler Group        Cupertino, CA USA  95014-2083
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