Re: objc_next_class

[Richard Frith-Macdonald]

I'm not sure what the original problem is, but just in case it's not 
obvious,
the code would fail (as Nicola notes below) because it would raise an
exception and crash as it iterates past the Object class -
NSLog() uses the -description method to log the class 'cl', but Object
does not respond ot that method.
I don't know where Object would appear in the iterated list (I'd have
expected it to be right at one end).

Perhaps we should add a category of Object in GNUstep-base, to implement
-description for it?

On Friday, June 14, 2002, at 02:40 AM, Nicola Pero wrote:

> Definitely the NSLog call is causing problems - try adding a 'NSLog' 
> call
> before this code snippet (looks like the first call to NSLog is
> initializing something which is confusing objc_next_class() ... bug in 
> the
> runtime ?) ... I'd like to check if the new 3.1 runtime still has this
> problem (since I rewrote all that runtime code).
>
> Anyway - after adding a dumb NSLog call before the code, I get all the
> classes, except one of the last ones gives -
>
> error: Object (class)
> Object does not recognize respondsToSelector:
> Aborted
>
> not much you can do about it ...
>
> NSLog (@"%@", [Object class]);
>
> seems to be causing an error.
>
> Replacing the NSLog with
>
> NSLog (@"fail on %@\n", NSStringFromClass (cl));
>
> fixes this problem.
>
>
> Hope all that helps :-)
>
> Please post questions/bug reports etc to a mailing list, such as
> bug-gnustep@gnu.org, so that other people get the opportunity of taking
> part/commenting/reading.
>
>
> On Tue, 11 Jun 2002, Marko Riedel wrote:
>
> > Hi all,
> >
> > I am working on another example. I don't want to go into the details
> > until I have a working program.
> >
> > I have a question about objc_next_class. It used to work fine, but now
> > it no longer iterates over all classes. Here is the code that I am
> > using:
> >
> >     void *state = NULL;
> >     Class cl;
> >     id primitive;
> >
> >     while((cl = objc_next_class(&state)) != nil){
> >         if([NSStringFromClass(cl) hasPrefix:PRIM_CLASS_PREF]){
> >             primitive = [[cl alloc] init];
> >             NSLog(@"primitive %@ %@\n", cl, primitive);
> >             [prim setObject:primitive
> >                   forKey:[primitive primName]];
> >         }
> >         else{
> >             NSLog(@"fail on %@\n", cl);
> >         }
> >     }
> >     NSLog(@"last %@\n", cl);
> >
> > The output is as follows:
> >
> > Jun 11 17:57:40 ...[9998] fail on NSPrinter
> > Jun 11 17:57:40 ...[9998] last (nil)
> >
> > Where are all the other classes that I know are there, like NSObject,
> > NSString, NSDictionary etc.?
> >
> > What is going on here? I also tried class_table_next, but it doesn't
> > seem to be available in the distribution that I downloaded.
>
>
>
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