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Re: Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful
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Re: Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful


  • Subject: Re: Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful
  • From: Jean-Daniel Dupas <email@hidden>
  • Date: Wed, 6 Feb 2008 18:05:46 +0100



Structures don't have "magic invisible members":

@interface Foo {
}
@end

Foo *aFoo;
NSLog(@"Foo is a %@", aFoo->isa);

Notice how there is an "isa" member that is automatically put there, not unlike the way that a C++ object might have a vtable (or other internal plumbing for multiple inheritance).



Wrong. This will not work. Foo will not have a magic isa ivar, an is not a valid objc class.

You have to either:
1) inherit from a valid root class (NSObject).
2) add a "Class isa" ivar to your declaration.

See the NSObject declaration:

@interface NSObject <NSObject> {
    Class	isa;
}
...
@end
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  • Follow-Ups:
    • Re: Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful
      • From: glenn andreas <email@hidden>
References: 
 >Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful (From: John Engelhart <email@hidden>)
 >Re: Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful (From: Alastair Houghton <email@hidden>)
 >Re: Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful (From: John Engelhart <email@hidden>)
 >Re: Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful (From: Alastair Houghton <email@hidden>)
 >Re: Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful (From: John Engelhart <email@hidden>)
 >Re: Use of Mac OS X 10.5 / Leopards Garbage Collection Considered Harmful (From: glenn andreas <email@hidden>)

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