gistfile1.ru

# At first glance, this doesn't seem so useful.

def a
  def b
    'you called b'
  end
  'b is now defined'
end
# > b
# NameError: undefined local variable or method `b'...
# > a
# => "b is now defined"
# > b
# => "you called b"

# but taken another way...

def enter_building
  def enter_building
    "enter building"
  end
  # method is now redefined for subsequent calls

  "open roller door, " + enter_building
end
# > enter_building
# => "open roller door, enter building"
# > enter_building
# => "enter building"
# > enter_building
# => "enter building"