From: Caleb Clausen <vikkous@...>
Date: 2006-07-28T01:49:59+09:00
Subject: Re: Symbols are your friends

On 7/27/06, Daniel Schierbeck <daniel.schierbeck@gmail.com> wrote:
> Yes, it's time for another Symbol trick!
>
>    class Symbol
>      def ===(obj)
>        obj.respond_to? "to_#{self}"
>      end
>    end

This idea has been discussed on this list before; I can't find the
thread at the moment.
This seems like a really clever idea, and is fine for just playing
around... but it's not advisable for general use. You're changing the
semantics of Symbol#===, which will break things like this:

case method_name
when :reverse
  #....
when :each
  #...
else #.....
end

The following is a simplified extract of what I use in Reg for a
similar feature. It's safer, as long as nothing else decides to do
something with Symbol#-@.

class Symbol
  def -@; Reg::Knows.new(self) end
end

module Reg
  class Knows
    def initialize(sym)
       @sym=sym
    end
    def ===(other)
      other.respond_to? @sym
    end
  end
end


(You're prepending "to_" to your method names before checking; I don't
know why. This way seems more general....)