Selectors and categories in GNUstep (porting from Cocoa)

[Andreas Hoeschler]

Hi all,

this is my first serious attempt to port some code to GNUstep. While 
stuff like the following works great on MacOSX

#define FBQualifierOperatorEqual @selector(isEqualTo:)
if ([object respondsToSelector:FBQualifierOperatorEqual]) ...

it does not under GNUstep. For example [dic 
respondsToSelector:@selector(name)] returns yes, where name is a 
dictionary. NSSelectorFromString(...) often returns nil while I get back 
a selector under MacOSX. Is there any other better working approach to 
get a selector from a string?

There also seems to be a problem with categories. Implementing a method 
qualifierForObject in a category or FBEntity

@implementation FBEntity (QualifierGeneration)

- (FBQualifier *)qualifierForObject:(FBObject *)object
{
   NSArray *attributeNames = [self primaryKeyAttributeNames];
   switch ([attributeNames count])
...
}

@end

leads to the following warnings.

FBQualifier.m: In function `-[FBEntity(QualifierGeneration) 
qualifierForObject:]':
FBQualifier.m:90: warning: suggest parentheses around assignment used as 
truth value
FBQualifier.m: In function `-[FBRelationship(QualifierGeneration) 
destinationQualififerForObject:]':
FBQualifier.m:120: warning: suggest parentheses around assignment used 
as truth value
FBQualifier.m:132: warning: suggest parentheses around assignment used 
as truth value
FBQualifier.m: In function `-[FBKeyValueQualifier evaluateWithObject:]':
FBQualifier.m:390: warning: cannot find method.
FBQualifier.m:390: warning: return type for `isEqualTo:' defaults to id

What does this mean? Am I missing anything? How can this be fixed?

Thanks a lot,

   Andreas