Re: Why aren't my bindings firing?
Re: Why aren't my bindings firing?
- Subject: Re: Why aren't my bindings firing?
- From: "Hamish Allan" <email@hidden>
- Date: Tue, 8 Jul 2008 16:33:54 +0100
On Tue, Jul 8, 2008 at 5:29 AM, Ron Lue-Sang <email@hidden> wrote:
> KVB is an informal protocol. So Cocoa Bindings™(R) provides a concrete
> implementation (on NSObject) of the KVB protocols.
> In addition to providing a KVB implementation, Cocoa Bindings(R)™ adds a set
> of reusable controllers to Cocoa.
The penny drops! Thank you, Ron.
The docs (http://developer.apple.com/documentation/Cocoa/Conceptual/CocoaBindings/Concepts/WhatAreBindings.html),
in answer to the question "What Is A Binding?", state that "a binding
is an attribute of one object that may be bound to a property in
another such that a change in either one is reflected in the other."
But there is also another type of binding, which I have since found
referred to in the docs as "Read-Only"
(http://developer.apple.com/documentation/Cocoa/Reference/CocoaBindingsRef/Concepts/BindingTypes.html),
in which the change is only reflected in one direction. NSObject
provides an implementation of this, which I had previously thought of
as a "pure" key-value binding, whereas I thought of the description
above as referring to "Cocoa bindings" (partly because if I were
writing the two-way implementation, I would build it atop the
unidirectional implementation, just as the docs state that Cocoa
Bindings are built on KVB). But I now understand that both types of
bindings are actually Cocoa Bindings.
Scott, for what it's worth, I really don't agree with you that Cocoa
Bindings and KVB are "the same thing" or that "there is no
distinction". I now understand that they are not two different types
of bindings: indeed, that neither of them is a type of binding. But if
you're wondering why this thread has gone on for longer than it should
have done, it's partly because your repeated assertion of their
equivalence has drawn my attention away from what your colleagues have
been trying to point out to me: that KVB is merely the informal
protocol, whereas the various implementations (and what I would call
"types" of binding) are all provided by Cocoa Bindings(R)™.
Thank you also to everyone else who replied.
Hamish
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