From: Edgardo Hames <ehames@...>
Date: 2009-04-14T06:45:04+09:00
Subject: Re: a few thoughts for ruby...

On Apr 11, 2:27 pm, Adam Gardner <adam.oddfel...@gmail.com> wrote:
> Roger Pack wrote:
> > Thought I'd pass these thoughts by the readers here before sending them
> > to core.  They're my current wish list :)
>
> > 1) add an Object#in? method to complement the existing Array#include?
>
> Object#in? can be very useful in keeping code legible; it more likely to
> be problematic in some circumstances than others. I'm using it in the
> game I'm writing right now and it's working just fine, but I don't
> really think it should be part of Ruby Core.
>
> That said, it's very very easy to add yourself if you need it:
>
> class Object
>   def in?(object)
>     if object.respond_to?(:include?) then
>       object.include? self
>     else
>       false
>     end
>   end #def in?
> end #class Object

Before reading your email I was writing my own Object#in? and came up
with a very similar method without testing :include? support:

class Object
  def in?(collection)
    collection.include? self
  end
end

This way you can detect you're calling Object#in? with an "incorrect"
argument. For example,

3.include? [1,2,3] => true
3.include? 5 => NoMethodError: undefined method `include?' for
5:Fixnum

My $0.02.

Best regards,
Edgardo