Ah all these rules!.rb

#Developer code:

def add
  1 + 1
end

# After another developer comments on the code with
# "1 is a magic number!"

def add
  a + b
end

# After another developer comments on the code with
# "It's not clear what a and b are!"
class Adder
  A = 1
  B = 2

  def add
    first_letter_of_the_alphabet + second_letter_of_the_alphabet
  end

  def first_letter_of_the_alphabet
    A 
  end

  def second_letter_of_the_alphabet
    B
  end
end

# SO CLEAN CODE, MUCH CLEAR, VERY EFFICIENT! 



# After showing this to a colleague!
# Seperation of concerns, the implementation of add shouldn't know about how to actually ADD the two numbers

DEFAULT_ADDITION_FUNCTION = :+

def add(function = DEFAULT_ADDITION_FUNCTION)
 first_letter_of_the_alphabet.send(function, second_letter_of_the_alphabet)
end

Customer request, add 3 to 1 and 2.

😄

This code directly returns the result. It's better to do something like 'lazy calculation': the actual calculation should be executed, when the result is used.