On Wed, Aug 13, 2008 at 8:39 PM, Rua Haszard Morris <[EMAIL PROTECTED]> wrote: > I'd like to get an error, not just a warning, when I pass an instance of a > class to a method that takes a parameter conforming to some protocol, and > the passed object does not implement the protocol. Is this possible? Is > there a good way to set things up so an error is generated.. or is there > some dynamism reason why a warning is more suited?
As far as I know, there's no way to make this one thing into an error. Objective-C is based around the idea of duck typing. This is just a funny way of saying that the type of an object is irrelevant. All that matters is what methods it implements (i.e. what it can do; if it looks like a duck, quacks like a duck, then it's a duck). As such, *all* static typing information in an Objective-C program is strictly advisory in nature. Code like this is perfectly legal, although weird: NSString *array = [NSArray arrayWithObject:@"hello"]; NSLog(@"%@", [array lastObject]); Now, protocols are supposed to *be* an indicator of capabilities rather than of type, but the same principle still applies to the use of protocols as part of static types. For example, you could implement the protocol methods without actually declaring conformance to the protocol. That said, good code should compile with no warnings anyway. I don't treat warnings much differently from errors. Occasionally I will tolerate a warning during development, for expediency or to denote something that I need to change later, and I am occasionally forced to accept warnings in external code that I didn't write but that I compile, but overall I treat warnings the same as errors, so the difference is not all that important to you. If you follow this approach but still want an actual stop-the-compile *error*, then you may be interested in the -Werror flag. This turns *all* warnings into errors, not just this one, but then again that may very well be a good thing. Mike _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
