> On Jun 16, 2017, at 4:32 PM, Quincey Morris > <quinceymor...@rivergatesoftware.com> wrote: > > On Jun 16, 2017, at 13:48 , Charles Srstka <cocoa...@charlessoft.com > <mailto:cocoa...@charlessoft.com>> wrote: >> >> This is incorrect. > > It’s incorrect as a 2-way binding, but it works as a pair of so-called 1-way > bindings, with the proviso that they may need to be unbound manually, to > prevent reference cycles, which it sounds like is what Jerry is doing. > > The thing that I always said that no one believed is that there’s really no > such thing as 1-way binding, and NSObject’s default implementation of the > “bind:…” method does *not* establish a binding. It’s *part* of the > implementation of a proper 2-way binding (as explained in the documentation > you referenced), and for a given receiver class the method only establishes a > 2-way binding if it’s an override that provides the rest of the functionality. > > But every time I said that (until I stopped saying it about 10 years ago), > people would jump in and say that the NSObject implementation really does > establish a binding, and if it’s only one-way, that’s > just-fine-with-them-thank-you-very-much. > > Thanks for the mention of mmalc, BTW. Them were the times. <elderly cough>
The thing is, though… I can’t find the thread anymore, but I distinctly remember posting some code that used -[bind:::] two ways like that, and getting chewed out for it. :-P The thing is, NSObject’s implementation of bind is meant to be part of a two-way bindings mechanism to be fully implemented by a view object, and it’s not really meant to be called outside of that context—and on top of that, it’s preferred that bindings go either through an NSObjectController, an NSViewController, or something else that implements NSEditorRegistration. Just using using -bind twice both ways between two arbitrary objects may accidentally work, but it’s not as intended. If all you want to do is synchronize some properties on two distinct objects, you’re supposed to use plain old KVO for that (as you mention, the new closure-based API in Swift is quite nice for doing this). And I did manage to find a quote for that last bit, by none other than mmalc himself: https://lists.apple.com/archives/Cocoa-dev/2004//Feb/msg01228.html <https://lists.apple.com/archives/Cocoa-dev/2004//Feb/msg01228.html> Charles _______________________________________________ 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: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
