Not that I want to respond to myself, but I want to correct:
You'll "get a warning" if an action call is not implemented by NSObject. Sorry for the confusion!Also, I want to state that I do feel that id is a very useful thing, despite how my first paragraph below makes it sound. But that's just my own opinion.
Cheers,
Andrew
On May 22, 2008, at 10:16 AM, Andrew Merenbach wrote:
Hi, John,There have been discussions on this list in the past, some of which might (or might not!) be helpful. Some, IIRC, lapsed into debate as to whether the "id" concept (a) was a bad idea, (b) was useless, (c) was confusing, or (d) made things difficult. Basically, "id" isn't exactly a type -- just a typedef. In objc.h:typedef struct objc_class *Class; typedef struct objc_object { Class isa; } *id;So it's basically a typedef for an Objective-C object. It's *not*, however, "equivalent" entirely to, say using NSObject *, since if NSObject doesn't implement a method, you'll get a warning. For instance:id del = [NSApp delegate]; [del myAction]; is not the same as: NSObject *del = [NSApp delegate]; [del myAction];As long (IIRC) as you #import your application delegate's header (in this example) into the .m file that contains the first two lines of above code, the compiler will say, "well, there's a method of this name -- perhaps this id refers to it. I won't throw a warning!" With the NSObject version, however, you'll absolutely get a warning. Also, I believe that the id typedef can also point to objects that are *not* descendants of NSObject, which may or may not be of relevance to you, but is a good point, IMHO.There are other advantages, IIRC, and possibly some disadvantage, but I can't think of them off the top of my head.Hope this helps! Cheers, Andrew On May 22, 2008, at 10:05 AM, john darnell wrote:Okay, this is a really basic question, but I need some help figuring outwhat the code wants.In the documentation for NSTableView, I am told that I must implement aspart of a datasource the following function: - (id) tableView:(NSTableView *) aTableView objectValueForTableColumn: (NSTableColumn *) aTableColumn row: (int) row { /* some code here */ return id; } The question is, what does the code want me returning as an id?I tried to do a search in Cocoa Help on id and as you might imagine, Igot lots and lots of hits, none of which looked anywhere near what I wanted for an explanation of what id is. So what is the framework expecting me to return? R, John A.M. Darnell Team Leader Walsworth Publishing Company Brookfield, MO John may also be reached at [EMAIL PROTECTED] Trivia Question: In SciFi Channel's hit series, FARSCAPE, who played the voice of Pilot?Answer: The voice of Pilot was played by Lani Tupu, the same actor whoplayed the villain-turned-refugee, Crais. _______________________________________________ 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/andrew.merenbach%40ucla.edu This email sent to [EMAIL PROTECTED]_______________________________________________ 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/andrew.merenbach%40ucla.edu This email sent to [EMAIL PROTECTED]
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