On 8/20/08 11:06 PM, Michael Ash said: >It is a little known fact that when passing NULL (and by extension nil >or Nil) as a parameter to a vararg function, you *must* cast it to the >appropriate pointer type to guarantee correct behavior. > >Interestingly, Apple's vararg methods which use nil as a terminator >(such as dictionaryWithObjectsAndKeys:) make no mention of this in >their documentation, and have a great deal of officially sanctioned >sample code which doesn't use such a cast. (And none of my code uses >it either.) I suppose Apple must be implicitly making a stronger >guarantee about the pointer-ness of nil than the C language makes >about NULL.
gcc provides: "-Wstrict-null-sentinel (C++ only) Warn also about the use of an uncasted "NULL" as sentinel. When compiling only with GCC this is a valid sentinel, as "NULL" is defined to "__null". Although it is a null pointer constant not a null pointer, it is guaranteed to of the same size as a pointer. But this use is not portable across different compilers." and indeed: ---------- #import <Cocoa/Cocoa.h> int main(int argc, char *argv[]) { NSArray* foo = [NSArray arrayWithObjects:@"foo", @"bar", nil]; return 0; } ---------- $ g++-4.2 -Wformat=2 -Wstrict-null-sentinel /Users/sean/Desktop/test.mm /Users/sean/Desktop/test.mm:5: warning: missing sentinel in function call using "(id)nil" in place of "nil" fixes the warning. -- ____________________________________________________________ Sean McBride, B. Eng [EMAIL PROTECTED] Rogue Research www.rogue-research.com Mac Software Developer Montréal, Québec, Canada _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]