Re: [Rubycocoa-talk] Bindings working with notification from Ruby

[kimura w. <ki...@us...>]

Hi,

I'm sorry my reply is too late.

Tue, 12 Apr 2005 10:38:50 +0100, Jonathan Paisley wrote:
>Hi,
>
>After following the instructions on the FAQ [1], with a few fiddles, I 
>have got Cocoa bindings on a Ruby object to work well. Please let me 
>know what you think of these modifications - if they seem ok I'll try 
>to update the Wiki FAQ page.
>
>The main thing I wanted to support was notification from Ruby to Cocoa 
>upon changing a value in Ruby.
>

>The kvc_accessor meta-method takes care of wrapping the setter (key=) 
>with the Cocoa bindings notifications. If the setter is already 
>defined, it will be wrapped by the kvc_accessor:
>
>   class MyModel < OSX::NSObject
>     def foo=(value)
>       @foo = value
>       @foo_parsed = ... # do some parsing of foo
>     end
>
>     kvc_accessor :foo # wraps foo= with notification, also defines foo 
>reader method
>   end
>
>Now, in other code, if you do 'model.foo = "Something"', any GUI 
>objects bound will automatically update.
>

It's cool! If you allow, I will add kvc_accessor to RubyCocoa.

btw, Module#method_added enables to hook method definition. Following
code reverts a wrapper of a setter when the setter is overrided.


module NSBehaviorAttachment
  def kvc_accessor(*keys)
    # define setter if needed
    # alias setter to internal setter
    # define wrapper
    # alias wrapper to setter
  end

  def kvc_internal_setter(key)
    # returns wrapped setter name
  end

  def kvc_setter_wrapper(key)
    # returns wrapper name
  end

  def method_added(sym)
    return unless sym.to_s =~ /([^=]+)=\z/
    key = $1

    setter = kvc_internal_setter(key)
    wrapper = kvc_setter_wrapper(key)
    return unless method_defined?(setter) && method_defined?(wrapper)

    # do not re-alias wrapper 
    return if self.instance_method(wrapper) == self.instance_method(sym)

    # re-alias wrapper to setter
    alias_method sym, wrapper
  end
end



-- 
kimura wataru