Seeking to Understand

I think it could be useful to have a shortcut added to Objective-C which combines a keyword value observer relationship with an automatic assignment on value change.

It could be noted syntactically using a new assignment operator (=> in my example below):

SomeObject *foo = [SomeObject new];
AnotherObject *bar = [AnotherObject new];
bar.property => foo.changingProperty;


The goal would be to build an automatic connection such that whenever the value of “changingProperty” is modified for object “foo”, object “bar” gets a message equivalent to: [bar setProperty:foo.changingProperty].

This is, of course, not without potential difficulties. For example, a deeper property reference would mean more cases to automatically observe:

bar.property => foo.changingProperty.anotherProperty;


In that case, there should probably be two observers - one for foo.changingProperty and another for (obj).anotherProperty. If “changingProperty” modifies it’s value, then the new resulting value object needs to be observed for changes to it’s “anotherProperty” property, and finally the original assignment to bar.property would be re-issued with the new value.

(Note: Not saying my assignment operator is awesome.. it was just something to use in an example. :))

This entry was posted on Monday, September 15th, 2008 at 2:50 pm and is filed under Programming. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.