From: Stefan Matthias Aust <sma@3plus4.de>
Date: 2001-05-01T03:40:13+09:00
Subject: [ruby-talk:14447] How to do it the Ruby-way 1

Hi!

I'm still a Ruby newbie and wonder what is the best way to express the
following algorithm in Ruby: A cache shall provide a service to access
the contents of files so that files are read only once.

class Cache
  @@cache = {}
  def Cache.get(name)
    cache.fetch(name) {@@cache[name] = File.open(name).read}
  end
end

Or more abstract, I want to either return an existing value or store
and return some new value if it's not already in a Hash. In Smalltalk,
I'd have used #at:ifAbsentPut:.  With the above Ruby code, I dislike
the []= inside the block. Have I overlooked some Hash method?


BTW, what's the "official" way to test whether a certain key exists in
a Hash object?  That class provides has_key?, include?, key? and
member?.  Why are there four different methods?


bye
--
Stefan Matthias Aust \/ Truth Until Paradox