From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-10-21T17:46:21+09:00
Subject: Re: scope when reopening method

On Thu, Oct 21, 2010 at 10:36 AM, Rahul Kumar <sentinel1879@gmail.com> wrote:
> Yes, you have misunderstood. "meth" already has access to its own
> variables.
> There is an application that creates an instance of My.
> It also contains an array "arr". I'd like to refer to that array within
> the reopened "meth".
> I would also like to call some methods that are in my app from the
> reopened method.

OK. Clear.

>   # i create an array that is not inside My class. Its in my
> application.
>   arr = []
>
>   # this method belongs to my app, not to My class
>   def do_something str
>     puts str
>   end
>
>   m = My.new
>   def m.meth(str)
>     # access some other object in application scope
>     # arr can be instance variable or local variable in application
>     arr << str
>     do_something str # call some method in my app
>   end
>

You could create a closure around your global scope. For that, you
need to avoid keywords such as class and def, because those do not
create closures, but create a new scope. You can try something like
this:

irb(main):001:0> arr = [1,2,3]
=> [1, 2, 3]
irb(main):002:0> a = Object.new
=> #<Object:0xb7505264>
irb(main):003:0> class Object
irb(main):004:1> def metaclass; class << self; self; end
irb(main):005:2> end
irb(main):006:1> end
=> nil
irb(main):008:0> a.metaclass.instance_eval { define_method(:something)
{ "the array #{arr.inspect}"}}
=> #<Proc:0xb74d783c@(irb):8>
irb(main):009:0> a.something
=> "the array [1, 2, 3]"

Jesus.