Re: NULL SEL arguments in Jaguar?
Re: NULL SEL arguments in Jaguar?
- Subject: Re: NULL SEL arguments in Jaguar?
- From: Ali Ozer <email@hidden>
- Date: Sat, 24 Aug 2002 14:42:47 -0700
The AppKit release notes for Jaguar say this, under the heading "SEL
Arguments":
"Foundation has been inconsistent in its handling of NULL SEL
arguments in
the past. In 10.2, for applications linked on 10.2 or later, Foundation
raises exceptions in all functions and methods (such as NSObjects
-respondsToSelector:) that take SEL arguments if the SEL argument is
NULL."
I don't understand why this note is in the AppKit release notes, if it
only
applies to Foundation.
It apparently does not in fact apply to the AppKit. For example, the
NSBeginAlertSheet() function in the AppKit takes two SEL parameters,
didEndSelector and didDismissSelector, and the documentation has
always said
you should pass NULL in either of these parameters that you don't use.
I do
this, and I get no exceptions.
Typically NULL SELs, nil objects, etc are invalid arguments, unless
explicitly indicated as an allowed exception --- which they are in the
case of the sheet functions and methods. (Similarly nil target is a
special indication of first responder, etc).
I am not sure off the top of my head, but I believe there are a few
cases where this applies in the AppKit, such as nil actions, etc ---
hence the warning in the AppKit relnotes. You're right that it would
have been a good idea to include this in the Foundation release notes
as well, as it does apply to NSObject methods.
Ali
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