On Mon, Mar 16, 2009 at 8:34 PM, Martin Wierschin <mar...@nisus.com> wrote: >>> btw, this method doesn't have any parameter, it's definition is: >> >> Whether you need it or not, you must take it, because that's the method >> signature that NSTimer expects to call back. > > I don't want to confuse the issue for Stefan, as matching up selector/method > names exactly is obviously very important. However, is there actually any > issue when a dynamic method dispatch includes arguments not present in the > actual method declaration/definition?
Theoretically speaking, it *could* certainly break. There is no guarantee that things will work if the caller and callee disagree about the number or type of arguments. For example, you could have an ABI where the caller is responsible for setting up the stack but the callee is responsible for tearing it down, and tearing it down requires knowing the total size of the arguments. Realistically, this works on every existing platform where OS X runs, and on every platform where OS X would conceivably run. To additionally support this, it would be very difficult to support the existing semantics of a message to nil (returns 0 and otherwise does nothing) without an environment that allows argument mismatches in general. Furthermore, a lot of existing code passes no-argument selectors to places where an argument is expected, and such a change would break all of that. Lastly, many Apple methods which take a selector and an argument explicitly allow you to use a selector which takes no arguments, such as performSelectorOnMainThread:. In conclusion, feel free to pass around selectors which take no arguments even when they will be invoked with an argument. 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 arch...@mail-archive.com
