Thank you all for your patience and kindness in educating me. I appreciate it very much. I will sub-class which is what I have previously done. This was, for me, a bit of an experiment (which failed). But that's also a good result.
Thanks again. Peter On 2012-04-02, at 12:44 AM, Jens Alfke wrote: > On Mar 31, 2012, at 6:46 PM, Peter Teeson wrote: >> In my app there is only the one NSMatrix instance > > There's no way to tell, really. For all I know, the Open or Save panels might > use NSMatrix. > Or the Find panel or the font panel. Heck, I believe in the old days of > OpenStep, > menus were implemented as NSMatrixes of menu item cells. > > Also, if you ever need to add another different NSMatrix somewhere else in > your app, > you're now SOL because you'll now have to rip out the category method and > re-implement > your code the right way using subclassing. > >> Although I do [super drawRect] after my own drawing. > > That won't call the old NSMatrix drawRect, it'll call the drawRect of the > superclass of NSMatrix, > which is NSControl. You've effectively deleted the original NSMatrix drawRect > implementation, > so it's impossible to call it without some tricky gymnastics. One more time: > a category doesn't override > a method, it replaces it. It literally edits the class's method table to > replace the old function pointer with the new one. > The only way to properly override a method, in the OOP sense, is to make a > subclass. > > —Jens _______________________________________________ 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: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
