From: Luis Crespo <lcrespom@...>
Date: 2008-05-30T01:00:49+09:00
Subject: Constants in modules

Hello,

I need to do something like this (this is a simplified version of some
other code, of course, but I don't want to get you lost in details
unrelated to the problem):

module M

  CONST_A = { 'k1' => 'v1', 'k2' => 'v2' }
  CONST_B = invert_hash(CONST_A)

  def method1
    # Do something with CONST_A
    puts CONST_A
  end

  def method2
    # Do something with CONST_B
    puts CONST_B
  end

  def invert_hash(h)
    inverted = {}
    h.each_pair { |k, v| inverted[v] = k }
    inverted
  end

end

My intention is to be able to calculate CONST_B by invoking a method in
the module itself... but I get this error message:

tests.rb:4: undefined method `invert_hash' for M:Module (NoMethodError)
  from tests.rb:1

I have tried lots of combinations by prefixing the module name, using
::, using module_function, etc., but nothing has worked.

Is there a way to do this? Of course I know there are obvious
workarounds such as defining the method outside the module, but that
would be quite ugly... and there should be a way to use code in my own
module from my own module!!!

Thanks in advance for your help,

    Luis.
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