Re: isKindOf: - GSObjCIsKindOf

[Pascal Bourguignon]

Marko Mikulicic <mikulici@die.supsi.ch> wrote:
> Hello,
> 
> Is there a way, knowing the name of two classes, test for
> the isKindOf relation without istantiating the receiver object:
> 
> I have noticed that those methods in NSObject are defined so:
> 
> 
> - (BOOL) isKindOf: (Class)aClassObject
> {
>    return [self isKindOfClass: aClassObject];
> }
> 
> + (BOOL) isKindOfClass: (Class)aClass
> {
>    if (aClass == [NSObject class])
>      return YES;
>    return NO;
> }
> - (BOOL) isKindOfClass: (Class)aClass
> {
>    Class class = GSObjCClass(self);
> 
>    return GSObjCIsKindOf(class, aClass);
> }
> 

As you can see, there is  a class method named isKindOfClass:. You can
send this message to a class.  On another hand, all classes are always
instanciated, you don't loose  anything invoking them, meaning that if
for  syntactic reason  you need  to write  [MyClass class]  instead of
MyClass, there's no downside (AFAIK).

         [MyFirstClass isKindOfClass:MySecondClass]

 
 
> Is there a way other than using GSObjCIsKindOf
> directly to look if one class inherits from the other one ?
> 
> (I have no instances, only classes converted from strings).
 
If you only have the class name  at run time stored in a NSString, you
can use  the function NSClassFromString (found  in NSObjCRuntime.h) to
get the class with the given name.

    Class Class1=NSClassFromString(@"MyFirstClass");
    Class Class2=NSClassFromString(@"MySecondClass");
    if((Class1!=nil)&&(Class2!=nil)){
        return([Class1 isKindOfClass:Class2]);
    }else{
        return(NO);
    }

> Thanks
You're welcome. 


> Marko
__Pascal__


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