Re: Fast enumeration

[Jens Ayton]

On Feb 7, 2011, at 16:19, Dr. H. Nikolaus Schaller wrote:
> 
> 
> Just another idea I would like to propose for discussion
> is to follow the "bracket-style" of NS_DURING NS_HANDLER & NS_END_HANDLER
> macros (http://www.cocoadev.com/index.pl?ExceptionHandling)
> 
> I.e. something like:
> 
> #define FOREACH(TYPE, VAR, COLLECTION) { NSEnumerator *_e=[(COLLECTION) 
> objectEnumerator]; TYPE VAR; while((VAR = [_e nextObject])) {
> #define FOREACH_END } }
> 
> The benefit would be that it appears to be a little more safe against errors 
> than
> 
> if(i == 0)
>       foreach(...)
>               if(j == 0)
>                       ...
> else
>       ...

The macros I posted have the same rules WRT braces as a normal for loop. If 
you're going to use FOREACH_END, you might as well use FOR_END and IF_END 
macros, or - more practically - require every if body to use braces.


> Finally, I think it should also be possible to rename the internal
> variable _e by macro name generation
> so that nested enumerations have private enumerator variables.
> 
> Something like ... NSEnumerator *_e##VAR;

This isn't necessary; nested enumerations each have their own scope.


-- 
Jens Ayton