Re: Setter Gettor method style

[Pascal Bourguignon]

> From: Martin =?iso-8859-1?Q?H=E4cker?= <mhaecker@mac.com>
> Date: Sat, 3 Aug 2002 11:27:08 +0200
> 
> Hi there!
> 
> Sorry if I spring in here, but I'd like to ask you about a topic wich 
> was discussed in depth on the Apple Cocoa Mailing list lately:
> 
> The question was how getter setter methods are written and they came 
> to the conclusion that these are the way's:
> 
> --- snip ---
>   Method 1: The following pair is good if performance of "get" is 
> important (say you expect it to be called it thousands of times a 
> second):
> 
>   - (NSString *) title {
>        return title;
>   }
> 
>   - (void) setTitle: (NSString *)newTitle {
>        [title autorelease];

Here, there  is not  advantage to wait  before releasing  title.  It's
owned by the object, it can  be released directly. If anybody has been
interested in title it will have  retained it long ago. Since title is
overwritten immediately, it cannot  be retrieved after this statement,
so you can as well use release.

>        title = [newTitle copy];
>        // or retain, depending on object & usage
>   }
> 
>   (as an optimization, you can do "if (title != newTitle)" in the set method).
> 
> 
>   Method 2: Otherwise use the following pair, where the return value 
> is autoreleased in the scope of the caller, which is more correct. 
> This is also more (but not fully) thread-safe as the returned value 
> is autoreleased in the calling thread.
> 
>   - (NSString *) title {
>        return [[title retain] autorelease];

This is strictly equivalent to { return title; }

>   }
> 
>   - (void) setTitle: (NSString *)newTitle {
>        if (title != newTitle) {
>                [title release];
>                title = [newTitle copy];
>                // or retain, depending on object & usage
>        }
>   }
> Ali Ozer
> --- snap ---
> 
> All this because of complicated manners which you can read about in 
> this thread:
> http://cocoa.mamasam.com/COCOADEV/2002/07/2/41217.php

[object retain] and [object  release] only increment and decrement the
retain count.   The fact  that release can  delete the object  in some
cases is irrelevant when the release count is greater than 1.

 
> Now, what I'd like to ask you is what you think about it and what 
> style is used in the GnuStep frameworks?

> Thanks a lot!
> 
> cu Martin
> -- 
> dont.wanna.tell
> [ot]coder - hehe


-- 
__Pascal_Bourguignon__                   http://www.informatimago.com/
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