From: Aaron Patterson <aaron@...>
Date: 2009-10-13T01:34:12+09:00
Subject: Re: Subclassing in module from top module?

On Oct 12, 2009, at 9:20 AM, Vít Ondruch wrote:

> Hello everybody,
>
> I would like to have locally monkeypatched Hash in my module. I would
> expect that following example will work, however it doesn't. How to do
> it correctly?

"local" and "monkeypatch" don't go together.  You can have a subclass  
though.

> irb(main):016:0> module Foo
> irb(main):017:1>     class Hash << ::Hash
> irb(main):018:2>         def bar
> irb(main):019:3>             puts 'bar'
> irb(main):020:3>           end
> irb(main):021:2>       end
> irb(main):022:1>   end
> SyntaxError: (irb):17: syntax error, unexpected tLSHFT, expecting  
> '<' or
> ';' or '\n'
>  class Hash << ::Hash
>               ^
>        from c:/Ruby/bin/irb:12:in `<main>'

Use one "<" to subclass Hash:

     module Foo
       class Hash < ::Hash
         ...
       end
     end

---
Aaron Patterson
http://tenderlovemaking.com