From: cremes.devlist@...
Date: 2006-12-05T02:33:10+09:00
Subject: help, my  'case/when' code doesn't work

I've been using ruby for several months now so imagine my surprise when I wrote something using the 'case' construct and I discovered that I didn't understand how to use it! What's worse is that even after looking through the Pickaxe and some code "in the wild" that uses 'case' I still don't see what I'm doing wrong.

Here's the code in question:

def case_test(obj)
  print "testing via case... "
  case obj.class
  when Array
    puts "obj is a #{obj.class}"
  when String
    puts "obj is a #{obj.class}"
  else
    puts "obj is unknown: #{obj.class}"
  end
end

def if_test(obj)
  print "testing via if... "
  klass = obj.class
  if klass == Array
    puts "obj is a #{klass}"
  elsif klass == String
    puts "obj is a #{klass}"
  else
    puts "obj is unknown: #{obj.class}"
  end
end

case_test(Array.new)
if_test(Array.new)
case_test(String.new)
if_test(String.new)
case_test(Hash.new)
if_test(Hash.new)
cremes$ ruby a.rb
testing via case... obj is unknown: Array
testing via if... obj is a Array
testing via case... obj is unknown: String
testing via if... obj is a String
testing via case... obj is unknown: Hash
testing via if... obj is unknown: Hash

What am I doing wrong here?