From: Daniel Berger <djberg96@...>
Date: 2005-05-23T01:10:17+09:00
Subject: Re: join not in Enumerable

Logan Capaldo wrote:
> Just a few minutes ago I was playing with irb as I am wont to do, and
> typed this:
>
> ('a'..'z').join(' ')
>
> Lo and behold it protested at me with a NoMethodError. I said to my
> self, self there is no reason that has to be Array only
functionality.
> Why isn't it in Enumerable? So I said:
>
> module Enumerable
>        def join(sep = '')
>             inject do |a, b|
>                      "#{a}#{sep}#{b}"
>             end
>         end
> end
>
> And then I said ('a'..'z').join(' ') and got:
> => "a b c d e f g h i j k l m n o p q r s t u v w x y z"
>
> #inject has to be the most dangerously effective method ever. But I
digress:
>
> Why is join, and perhaps even pack in Array and not in Enumerable?

Because there is nothing explicitly iterative about join.  Also, every
class except Array would have to have a custom definition of join,
since there's no reasonable default behavior for any class outside of
Array.  And if every class would have to implement its own version of a
method, that method doesn't belong in a module.  Modules are not
interfaces.

I can see that Ara has already found an excuse to give join a block -
lovely.  The slide continues....

Regards,

Dan