From: dblack@...
Date: 2006-03-08T05:47:41+09:00
Subject: Re: Accessing variables/constants from another file

Hi --

On Wed, 8 Mar 2006, saudaziz@gmail.com wrote:

> How can i access "myvariable" in the provided code from
>
> Say constants.rb has the following code
>
> Module
>
> myvariable = 'foo'
>
> end
>
> And another file driver.rb has following code
>
> require constants
>
> class myclass < food
>
> def busted
> #how can i call 'myvariable' constant here?
>
> end
>
> end

The whole idea of "local" variables is to be local :-)  If you want
something to be visible between files, you should make it a constant
or a method:

# constants.rb:

module M
   def M.my_value
     "foo"
   end
end

# driver.rb:

require 'constants'

class MyClass < Food
   def not_busted
     myvariable = M.myvalue
     # etc.
   end
end


or something like that.

> Also, if you can tell me what exactly is the difference between require
> and include, that would be great help. I don't see any clear
> explanation anywhere for the above.

"require" reads in a file (either a Ruby file or a compiled file for a
C extension).  "include" mixes a module into a class or into another
module.  So the usual sequence is require, then include: first you
read in the file that defines a module (like M in my example), then
you do something with the module (in my example I just used a method
in it, but you can also "include" modules).


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

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