40 lines
987 B
Objective-C
40 lines
987 B
Objective-C
@interface T : NSObject
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{ }
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- (void)identify;
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@end
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@implementation T
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- (void)identify {
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NSLog(@"I am a genuine T");
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}
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- (id)copyWithZone:(NSZone *)zone {
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T *copy = [[[self class] allocWithZone:zone] init]; // call an appropriate constructor here
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// then copy data into it as appropriate here
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// make sure to use "[[self class] alloc..." and
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// not "[T alloc..." to make it polymorphic
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return copy;
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}
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@end
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@interface S : T
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{ }
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@end
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@implementation S
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- (void)identify
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{
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NSLog(@"I am an S");
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}
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@end
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int main()
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{
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T *original = [[S alloc] init];
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T *another = [original copy];
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[another identify]; // logs "I am an S"
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[another release]; // like "alloc", the object returned by "copy" is "owned" by the caller, so we are responsible for releasing it
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[original release];
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return 0;
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}
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