From: Gennady Bystritsky <Gennady.Bystritsky@...>
Date: 2010-04-14T01:01:25+09:00
Subject: Re: scope limitation causes problems for me.


On Apr 13, 2010, at 8:41 AM, ±èÁØ¿µ 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??

In your code, m is defined as a local variable in the top scope, so it is not visible in methods. A straightforward fix would be to use $m instead of m, which will designate a global variable. However, I would strongly recommend to wrap your code in a class and have an instance variable @m which will be visible to every method of that class, thus avoiding evil global variables:

class Performer
  def initialize(default_value)
    @m = Hash.new(default_value)
    @m["b"] = "babo"
  end

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

Then you can call it as:

Performer.new("merong").func

Gennady.