I'm no fan of these newfangled Objective-C 2.0 features that you
whippersnappers seem so excited about (call me old fashioned), but I'm
giving properties a shot, especially now that I'm working on some
stuff for [REDACTED].
I've notice something strange with properties that I hope someone can
clear up for me. Either something is very, very wrong with
Objective-C 2.0, or I just haven't gotten enough sleep.
Say I have a class like so:
------------------
@interface MyTestClass : NSObject
@property (readonly) NSString *someProperty;
- (MyTestClass *)someMethod;
@end
@implementation MyTestClass
- (NSString *)someProperty
{
return @"Some String";
}
- (MyTestClass *)someMethod
{
NSLog(@"someMethod called");
return self;
}
@end
-----------------------
MyTestClass has one method, and one property.
Now, say I do something like this:
MyTestClass *o = [[MyTestClass alloc] init];
[o someMethod];
things work great. [o someMethod] gets called, logs, and returns
itself. Fantastic.
Of course, now I can do something like this:
MyTestClass *ret = [o someMethod];
NSString *s = ret.someProperty;
NSLog(@"got string %@", s);
Which, again, works as expected. My output looks like so:
> someMethod called
> got string Some String
Now, the confusing part. Say I smoosh together the above like so:
NSString *n = [o someMethod].someProperty; // this is where the
weirdness happens
NSLog(@"got string %@", n);
My output looks like this:
> someMethod called
> someMethod called
> got string Some String
Call me crazy, but I'm only calling [o someMethod] once in the above
code... so why is it getting called twice? Imagine my frustration
tracking down the bug when -someMethod has side effects :).
Interesting side note, calling the property with the normal
Objective-C syntax works fine like so:
NSString *m = [[o someMethod] someProperty];
NSLog(@"got string %@", m);
-- outputs --
> someMethod called
> got string Some String
Note that I've only tried this on [REDACTED], but imagine that it
works the same way on the desktop.
WTF?
Thanks,
Loren
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