Extending a module

correct_extend.rb

module ExtendMe
  def extension_method
    puts "Hello from ExtendMe!"
  end
end

class Klass
  extend ExtendMe
   
  def self.extended
    extension_method
  end
end

Klass.extended

# The above code will not produce an error and instead will print:
# "Hello from ExtendMe!"

wrong_extend.rb

# I learned a very valueable lesson today about extending a module

module ExtendMe
  def self.extension_method
    puts "Hello from ExtendMe!"
  end
end

class Klass
  extend ExtendMe
   
  def self.extended
    extension_method
  end
end

Klass.extended

## The above code will return an error saying local variable extension_method
# does not exits. This is because you cannot extend a module self.#{x} method
# You can only extend module methods that are instane methods like the in the correct_extend.rb file below