From: Marnen Laibow-Koser <marnen@...>
Date: 2009-11-16T14:45:25+09:00
Subject: Re: Newbie question:  Defining a numeric type

Seebs wrote:
> I have a type which has a bit of internal magic, but fundamentally, I 
> want
> it to behave for most purposes like the value it yields from 
> to_i/to_int.

Does it need to be a class of its own?  You could use a module and just 
include it where necessary:

module Magical
  def magic
  ...
  end
end
...
...
@val = 5
class << @val
  include Magical
end
@val.magic

> 
> Basically, is there a way to avoid having to write +, -, etcetera, when
> in each case it'd be:
>   def <op>(other)
>     self.to_i <op> other
>   end
>

If you don't like the first solution, try:

[:+, :*, :-, :/, :%].each do |op|
  define_method op {|other| self.to_i.send op, other}
end

You could wrap this in a module too.

> I think I'm thinking something like the Comparable mixin; sort of a
> "I have a to_i, make me a number" module.
> 
> -s

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen@marnen.org
-- 
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