From: Joel VanderWerf <vjoel@...>
Date: 2009-05-07T09:40:51+09:00
Subject: Re: How to get class' filepath from methods in included mixin?

Nigel Hennan wrote:
> Hi,
> 
> File.dirname(__FILE__) returns the current folder where the script in,
> How to get it from methods in included modules?
> 
> My sample code as below:
> 
> helper.rb
> ---------
> 
> module Helper
>   def your_path
>     puts instance_eval { File.expand_path(File.dirname(__FILE__)) } #
> doesn't work
>   end
> end
> 
> a.rb
> -----
> require 'helper/helper'
> 
> class A
>  include Helper
> end
> 
> A.new.your_path #=> return helper's file path, not class A's

This seems to work:

[~/tmp] cat helper/helper.rb
module Helper
   def self.included m
     file = caller[1][/(.*):\d+$/, 1] ## a bit fragile, maybe
     dir = File.expand_path(File.dirname(file))
     m.const_set "YourPath", dir
   end

   def your_path
     self.class::YourPath
   end
end
[~/tmp] cat a.rb
require 'helper/helper'

class A
  include Helper
end

p A.new.your_path
[~/tmp] ruby a.rb
"/home/vjoel/tmp"


-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407