[MacRuby-devel] [MacRuby] #409: Attribute setter should be accepted as KVO setter

[MacRuby]

#409: Attribute setter should be accepted as KVO setter
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 Reporter:  neeracher@…          |       Owner:  lsansonetti@…        
     Type:  enhancement          |      Status:  new                  
 Priority:  minor                |   Milestone:                       
Component:  MacRuby              |    Keywords:                       
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Comment(by dylan@…):

 *poke* I just ran into this one and traced it down. Any updates ?

 I've attached a project that shows a naive implementation with bindings
 that shows how someone could get into trouble with this.

 I think this is a little more severe than it appears at first glance. It
 violates the principle of least surprise in a big way; even something a
 simple as adapting example code to a new Mac interface will run afoul of
 this pretty quickly.

 Even if you're familiar with both Ruby and ObjC this generates some
 confusion since you can no longer use idiomatic ruby to change your model
 if you want it bound to the UI at any future date. You currently have to
 get used to always using the ObjC setValue way.

 If you're not familiar with both you're going to be scratching your head
 for a while.

 This is also insidious since your model unit tests will pass and only the
 less easily testable UI will fail, unless you set up explicit bindings
 tests for each property.

 That said, this may not be as simple a fix as it appears. My gut feeling
 was to override attr_accessor and writer to generate a value= method that
 just calls setValue. This works 95% of the time, but gets murky when you
 want to create a custom setter. Which do you override ? Do you always have
 to call setValue from your value= method ? How should it be documented if
 that's the case ? Of course, you still have that confusion the way it
 exists now. Going to implement value= and then finding that your bindings
 don't call that method, for instance.

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Ticket URL: <http://www.macruby.org/trac/ticket/409#comment:1>
MacRuby <http://macruby.org/>