On 3 Oct, 2009, at 23:51, Klaus Backert wrote:
On 3 Oct 2009, at 22:06, Colin Howarth wrote:
If you use dot notation and properties, you are using the -value
and -setValue: accessor methods, which is KVC compliant and means
that KVO bits will get notified, no?
No.
From the documentation "The Objective-C 2.0 Programming Language":
----------
You can think of a property declaration as being equivalent to
declaring two accessor methods. Thus
@property float value;
is equivalent to:
- (float)value;
- (void)setValue:(float)newValue;
A property declaration, however, provides additional information
about how the accessor methods are implemented
----------
Accessing using dot notation
myObject.value = x;
x = myObject.value;
is equivalent to accessing using conventional notation
[myObject setValue: x];
x = [myObject value];
This all may be something which is KVC compliant -- or it may not be
--, as you can see in the "Key-Value Coding Programming Guide",
chapter "Ensuring KVC Compliance".
OK, since this is perhaps a relevant example of what I was talking
about, let's compare my off the cuff sentence with the Apple Docs:
If you use dot notation and properties, you are using the -value
and -setValue: accessor methods, which is KVC compliant and means
that KVO bits will get notified, no?
Ensuring KVC Compliance
In order for a class to be considered KVC compliant for a specific
property, it must implement the methods required for valueForKey: and
setValue:forKey: to work for that property.
Attribute and To-One Relationship Compliance
For properties that are an attribute or a to-one relationship, this
requires that:
• Your class implements a method named -<key>, -is<Key>, or has an
instance variable <key> or_<key>.
• If the property is mutable, then it should also implement -set<Key>:.
• Your implementation of the -set<Key>: method should not perform
validation.
• Your class should implement -validate<Key>:error: if validation is
appropriate for the key.
<<< I have an instance variable named <key>. The methods -<key> and -
set<Key>: have been synthesized. Validation is inappropriate >>>
Indexed To-Many Relationship Compliance
For indexed to-many relationships, KVC compliance requires that your
class:
• Implements method named -<key> that returns an array.
• Or has an array instance variable named <key> or _<key>.
• Or implements the method -countOf<Key> and one or both of -
objectIn<Key>AtIndex: or -<key>AtIndexes:.
• Optionally, you can also implement -get<Key>:range: to improve
performance.
<<< I have an array instance variable named <key>. Performance is not
an issue. >>>
For a indexed ordered to-many relationship, KVC compliance requires
that your class also:
• Implement one or both of the methods -insertObject:in<Key>AtIndex:
or -insert<Key>:atIndexes:.
• Implement one or both of the methods -removeObjectFrom<Key>AtIndex:
or -remove<Key>AtIndexes:.
• Optionally, you can also implement -
replaceObjectIn<Key>AtIndex:withObject: or -
replace<Key>AtIndexes:with<Key>: to improve performance.
<<< Oooh, tut, tut. That should probably read "For a MUTABLE indexed
ordered to-many relationship", or, at least, "For AN indexed ..." >>>
Unordered To-Many Relationship Compliance
For unordered to-many relationships, KVC compliance requires that your
class:
• Implements method named -<key> that returns a set.
• Or has an set instance variable named <key> or _<key>.
• Or implements the methods -countOf<Key>, -enumeratorOf<Key>, and -
memberOf<Key>:.
<<< Ah. Little typo: "Or has A set". I don't have any set instance
variables, but if I did, they would be named <key>. >>>
For a mutable unordered to-many relationship, KVC compliance requires
that your class also:
• Implement one or both of the methods -add<Key>Object: or -add<Key>:.
• Implement one or both of the methods -remove<Key>Object: or -
remove<Key>:.
• Optionally, you can also implement -intersect<Key>: and -set<Key>:
to improve performance.
<<< I don't have a "mutable unordered to-many relationship" aka as a
"set" >>>
So, on the assumption that I have the relevant instance variables,
which I do, my statement is basically correct. Except that it doesn't
cover instance variables that are "mutable unordered or indexed and/or
ordered to-many relationships" - but then it (my statement) is a
little shorter, isn't it?
--colin
_______________________________________________
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
