From: Mark Hubbart <discordantus@...>
Date: 2005-05-18T12:13:15+09:00
Subject: Re: Noobie ... Simple Inheriting from Hash Question ..

On 5/17/05, David A. Black <dblack@wobblini.net> wrote:
> Hi --
> 
> On Wed, 18 May 2005, David Mitchell wrote:
> 
> > You could just extend the hash class, rather than inheriting from it. That
> > is, instead of this:
> >
> > class myHash < Hash
> >       def foo
> >               ...
> >       end
> > end
> >
> > Do this:
> >
> > class Hash
> >       def foo
> >               ...
> >       end
> > end
> >
> > Then, all your hash objects will be given your 'foo' method and you can do
> > things like this:
> >
> > {:key => "value"}.foo
> 
> This will work but also suffers from the usual problem with extending
> core classes -- namely, it's unsafe to do unless you're sure
> that your code will run in isolation.
> 
> Another possibility is to add the behavior on a per-object basis:
> 
>    module MyHashStuff
>      def foo
>        # ...
>      end
>    end
> 
>    h = {1,2,3,4}
>    h.extend(MyHashStuff)
>    h.foo                  # h now has the food method

Another option is to add a to_myhash method to Hash:

class MyHash < Hash
  def foo
    ...
  end
end

class Hash
  def to_myhash
    MyHash.new.update self
  end
end

Now you can create myhashes like this:

{1=>2,3=>4}.to_myhash

cheers,
Mark