lexical_scope.rb

#!/usr/bin/env ruby
require 'test/unit'

CONSTANT = :global

module A
  CONSTANT = :lexical
  
  class B
    def constant
      CONSTANT
    end
  end
end

module A
  class C
    def constant
      CONSTANT
    end
  end
end

# I know it happens, from experience, but I've never understood why declaring
# a class inside a module with the scope operator doesn't open up the lexical
# scope of the enclosing module (see the example below). So, why?
class A::D
  def constant
    CONSTANT
  end
end

class LexicalTest < Test::Unit::TestCase
  def test_b
    assert_equal :lexical, A::B.new.constant
  end

  def test_c
    assert_equal :lexical, A::C.new.constant
  end

  def test_d
    assert_equal :global, A::D.new.constant
  end
end