On Jan 22, 2013, at 2:19 PM, Charles Srstka <cocoa...@charlessoft.com> wrote:
> On Jan 22, 2013, at 12:58 PM, Andy Lee <ag...@mac.com> wrote:
>
>> // Or this also works (protocol).
>> @protocol AvoidCompilerWarning
>> - (id)initWithArg:(id)arg;
>> @end
>
> Really, a protocol is what you ought to be doing. Make a protocol with
> -initWithManager: in it, and then make all the classes that might get passed
> to this method comply with your protocol. Then, do this:
>
> if ([myClass conformsToProtocol:@protocol(MyProtocol)])
> myObj = [[myClass alloc] initWithManager:sel]];
> else
> myObj = [[myClass alloc] init];
>
> The advantage to this method is a simple one: Suppose some random class
> happens to implement a method named -initWithManager:, but that method has
> nothing to do with your -initWithManager: other than a coincidental title,
> and takes a completely different type of object. Your original code will
> result in unpredictable behavior in this case (and probably throw an
> exception leading to a crash). If you use a protocol, you'll know not just
> that the method responds to something named -initWithManager:, but that it's
> *your* -initWithManager:
Makes sense, especially since it sounds like you have enough control of the
class to declare it as conforming to the protocol.
To be extra fail-safe, you might want to perform a cast to be sure the right
initWithManager: gets called:
if ([myClass conformsToProtocol:@protocol(MyProtocol)])
myObj = [(id <MyProtocol>)[myClass alloc] initWithManager:self];
else
myObj = [[myClass alloc] init];
--Andy
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