From: nobu.nokada@...
Date: 2002-05-29T21:35:56+09:00
Subject: Re: Idioms

Hi,

At Wed, 29 May 2002 20:58:59 +0900,
Stephan J. Schmidt <stephan.schmidt@neotis.de> wrote:
> Could someone point me to idioms about ruby, e.g. 
> something shorter to
> 
> if not hash.key?(key)
>   hash[key] << value
> end 

If you want to add `value' only when the `hash' doesn't have
the `key':

  hash.fetch(key) {hash[key] = [value]}

  hash[key] ||= [value]

If you want to add `value' to the `hash' with making a list
automatically:

  (hash[key] ||= []) << value

  hash.fetch(key) {hash[key] = []} << value

  hash = Hash.new([])
  hash[key] += [value]

  # 1.7 feature
  hash = Hash.new {|h, i| h[i] = []}
  hash[key] << value

-- 
Nobu Nakada