From: Robert Dober <robert.dober@...>
Date: 2008-09-02T21:08:57+09:00
Subject: Re: Does this seem useful for you?

On Tue, Sep 2, 2008 at 1:04 PM, Jens Wille <jens.wille@uni-koeln.de> wrote:

>> "abcd".map_messages( [ :[], 1, 2], :size )
> done. more or less ;-) i kept hashes, since i sometimes like 'em
> better. would you prefer === over is_a? in this case? if so, why?

Although is_a? is more readable the #=== operator is a very powerful
concept of ruby, using it and thus understanding its semantics allows
us to use/understand case statements more efficiently, a problem that
frequently comes up with nubies.
I guess most people prefer this code

case args.first
when String, Symbol
  ...
when Enumerable
  ...
end

to

if args.first.is_a?( String ) || ...
 ...
elsif args.first.is_a?( Enumerable )

end

Somehow I feel therefore the use of Class#=== preferable to
Object#is_a? but I would not argue with people using is_a? ;).

R.