From: James French <James.French@...>
Date: 2009-10-03T00:50:55+09:00
Subject: Re: operating on a selection of objects

Brilliant. Thanks!

> -----Original Message-----
> From: Jesús Gabriel y Galán [mailto:jgabrielygalan@gmail.com]
> Sent: 02 October 2009 16:28
> To: ruby-talk ML
> Subject: Re: operating on a selection of objects
> 
> On Fri, Oct 2, 2009 at 4:54 PM, James French
> <James.French@naturalmotion.com> wrote:
> > Hi,
> >
> > I want to be able to do operations to a selection of objects,
> something like this:
> >
> > class Config
> >  attr_accessor :name
> > end
> >
> > class ConfigSelection
> >
> >  def initialize(*configs)
> >    @configs = configs
> >  end
> >
> >  def name=(n)
> >    @configs.each{|c| c.name = n}
> >  end
> >
> > end
> >
> > a = Config.new
> > a.name = "a"
> >
> > b = Config.new
> > b.name = "b"
> >
> > s = ConfigSelection.new(a, b)
> > s.name = "s"
> >
> >
> > I was wondering if there might be a more elegant way of doing this,
> without having to explicitly duplicate all of Config's attributes in
> ConfigSelection?
> 
> This is a way, with the restriction that it only checks instance
> methods defined in the class:
> 
> irb(main):015:0> c = Config.new
> => #<Config:0xb7db3f78>
> irb(main):016:0> c.name="test"
> => "test"
> irb(main):017:0> c2 = Config.new
> => #<Config:0xb7dad038>
> irb(main):018:0> c2.name = "test2"
> => "test2"
> 
> irb(main):041:0> class ConfigSelection
> irb(main):042:1> def method_missing meth, *args, &blk
> irb(main):043:2> if Config.instance_methods.include? meth.to_s
> irb(main):044:3> @configs.each {|c| c.send meth, *args, &blk}
> irb(main):045:3> else
> irb(main):046:3* super
> irb(main):047:3> end
> irb(main):048:2> end
> irb(main):049:1> end
> => nil
> irb(main):050:0> csel = ConfigSelection.new c,c2
> => #<ConfigSelection:0xb7d9c198 @configs=[#<Config:0xb7db3f78
> @name="test">, #<Config:0xb7dad038 @name="test2">]>
> irb(main):051:0> csel.name="changed"
> => "changed"
> irb(main):052:0> csel
> => #<ConfigSelection:0xb7d9c198 @configs=[#<Config:0xb7db3f78
> @name="changed">, #<Config:0xb7dad038 @name="changed">]>
> 
> Hope this gives you some ideas,
> 
> Jesus.