From: "Mauricio Fernández" <batsman.geo@...>
Date: 2003-05-17T04:01:06+09:00
Subject: Re: procs and context

On Sat, May 17, 2003 at 02:43:57AM +0900, repeatr wrote:
> def method_missing(action)
>   puts "#{action}...in the city"
> end
> 
> class Room
>   def method_missing(action)
>     puts "#{action}...in the the privacy of your own room"
>   end
> 
>   def live(&block)
>     instance_eval { Proc.new.call }

Proc.new reifies the passed block, which was already bound to the
external context. Use instance_eval(&block). Note however that only the
value of self is substituted, ie.:

batsman@tux-chan:/tmp$ expand -t2 ag.rb
class Foo
  def bar(&block)
    a = "inner a"
    instance_eval(&block)
  end
end

a = "external a"
o = Foo.new
o.bar do
  puts "self.id: #{self.id}"
  puts "a is #{a.inspect}"
end
puts "o.id:    #{o.id}"
batsman@tux-chan:/tmp$ ruby ag.rb
self.id: 537725500
a is "external a"
o.id:    537725500

>   end
> 
>   def initialize
>     put_feet_on_table
>     snore
>   end
> end
> 
> walk
> go_to_work
> 
> room = Room.new
> room.live do
>   walk_around_naked!
> end
> --------------
> 
> output:
> walk...in the city
> go_to_work...in the city
> put_feet_on_table...in the the privacy of your own room
> snore...in the the privacy of your own room
> walk_around_naked!...in the city

LOL
We *have to* put this in some tutorial or documentation!

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