Rails - Jun 2006 - Adding a instance method

Hi all,

I''d like to add a instance method to class String.

I should be fairly simple with

class String; def newmethod; do_something ; end; end

and it works perfectly if I test this independently with irb.
However if I add this to my application.rb I''ll get an error like

(undefined method `newmethod'' for "123456":String)

What''s wrong with that?
Thanks
Jens

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Hi --

On Sun, 18 Jun 2006, Jens wrote:
> Hi all,
>
> I''d like to add a instance method to class String.
>
> I should be fairly simple with
>
> class String; def newmethod; do_something ; end; end
>
> and it works perfectly if I test this independently with irb.
> However if I add this to my application.rb I''ll get an error like
>
> (undefined method `newmethod'' for "123456":String)
>
> What''s wrong with that?
If you do this:

   class ApplicationController < ActionController::Base
     class String

you''re creating a new String class nested inside
ApplicationController.  If you want to get into the top-level String
class, you can put the code at the top:

   class String
     # stuff here
   end

   class ApplicationController < ActionController::Base

or you can use the path notation to force a top-level constant:

   class ::String

Another option is to put the code in a separate file in the lib
subdirectory of your application, and then ''require'' it at
runtime.
That''s probably a cleaner design.

(And don''t forget the many pitfalls of modifying core classes :-)


David

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

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David,

Yep, makes total sense! Thanks a lot for the detailed answer
All the best
Jens

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