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[objc-improvements] Just remembered something about multiple method sign
From: |
Ziemowit Laski |
Subject: |
[objc-improvements] Just remembered something about multiple method signatures... |
Date: |
Fri, 5 Sep 2003 11:38:28 -0700 |
I just remembered a weird corner case that was really occurring in
Apple's code. Namely, you had several conflicting method signatures,
one of which was returning 'void', while others were returning assorted
non-void values. It just so happened that the 'void' guy was seen last,
and so the compiler happily plucked it from the hash table. But this
was
a wrong choice, resulting in a cascade of errors when we tried to assign
the result of the message dispatch.
At the time, my fix was to special case method dispatching: If it was
determined that the return type should be 'void', substitute an 'id'
return type instead. :-) Not pretty, but it worked.
I guess my point is that arbitrarily picking a signature out of a pool
of contenders is fraught with problems, and I still believe that
the IMP fallback is a cleaner solution in this case. I don't think
doing this breaks (codegen-wise) the counterexample you guys keep
discussing (i.e., where all the candidate methods return
NSComparisonResult),
does it?
--Zem
--------------------------------------------------------------
Ziemowit Laski 1 Infinite Loop, MS 301-2K
Mac OS X Compiler Group Cupertino, CA USA 95014-2083
Apple Computer, Inc. +1.408.974.6229 Fax .5477
- [objc-improvements] Just remembered something about multiple method signatures...,
Ziemowit Laski <=
- Re: [objc-improvements] Just remembered something about multiple method signatures..., David Ayers, 2003/09/06
- Re: [objc-improvements] Just remembered something about multiple method signatures..., Chris Hanson, 2003/09/07
- Re: [objc-improvements] Just remembered something about multiple method signatures..., Ziemowit Laski, 2003/09/07
- Re: [objc-improvements] Just remembered something about multiple method signatures..., David Ayers, 2003/09/08
- Re: [objc-improvements] Just remembered something about multiple method signatures..., Ziemowit Laski, 2003/09/08
- Re: [objc-improvements] Just remembered something about multiple method signatures..., Pete French, 2003/09/09
- Re: [objc-improvements] Just remembered something about multiple method signatures..., Nicola Pero, 2003/09/09
- Re: [objc-improvements] Just remembered something about multiple method signatures..., David Ayers, 2003/09/09
- Re: [objc-improvements] Just remembered something about multiplemethod signatures..., Alexander Malmberg, 2003/09/08
- Re: [objc-improvements] Just remembered something about multiplemethod signatures..., Ziemowit Laski, 2003/09/08