Re: warning: assignment from distinct Objective-C type
Re: warning: assignment from distinct Objective-C type
- Subject: Re: warning: assignment from distinct Objective-C type
- From: "Dennis C. De Mars" <email@hidden>
- Date: Wed, 12 Mar 2008 09:26:03 -0700
On Mar 11, 2008, at 3:59 PM, j o a r wrote:
On Mar 11, 2008, at 3:49 PM, Quincey Morris wrote:
Personally I prefer the factory method approach, a la [NSArray
array] etc:
Note that factory class methods typically also return id for the
same reason that init methods return id (NSArray, NSString, et.c.).
This in contrast to shared instances that are strongly typed
(NSFileManager, NSHost, NSNull, et.c.).
Tthere are quite a few Cocoa classes where the factory method is
strongly typed.
The cases where the factory method returns (id) are generally (but not
always) the classes that are likely to be subclassed or in fact are
already subclassed in the existing Cocoa hierarchy. This would
automatically include any class that has a "mutable" variation. In
these cases, the return is typed (id) because you do not, in fact,
know what the type of the object is that the method will return in
general.
In other cases, I think the class is either unlikely to be subclassed
or it is not advisable to subclass it, and these tend to have strongly
typed factory methods.
Examples:
NSAffineTransform:
-transform
NSBundle:
-bundleWithPath:, etc.
NSNumber:
all "numberWith..." methods
NSValue
all "valueWith..." methods
NSColor
all "colorWith..." methods
... and many more.
- Dennis D.
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