From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-04-14T00:55:13+09:00
Subject: Re: scope limitation causes problems for me.

On Tue, Apr 13, 2010 at 5:41 PM, 김준영 <juneng603@gmail.com> wrote:
> hi, everyone.
>
> I have the following codes.
>
> m = Hash.new("merong")
>
> m["b"] = "babo"
>
> def func
>    begin
>        m["a"] = "merong"
>    rescue => e
>        puts e
>    end
> end
>
> func
>
>
>
> exception is
>
> undefined local variable or method `m' for main:Object
>
> Could I know the reason this was caused??

The reason is that the def keyword starts a new scope, and doesn't
inherit the surrounding scope (it's not a closure). You could pass the
hash as a parameter to the function for example:

m = Hash.new("merong")
m["b"] = "babo"

def func hash
   begin
       hash["a"] = "merong"
   rescue => e
       puts e
   end
end

func m

Or use define_method, if you really wanted a closure over that scope:


m = Hash.new("merong")
m["b"] = "babo"

self.class.send (:define_method, :func) do
   begin
       m["a"] = "merong"
   rescue => e
       puts e
   end
end

func

Jesus.