stupid_include_sample.rb

# File: person_module.rb
module Person
  def age
    Time.now - self.birthday
  end
end

# File: main.rb
require 'person_module'

class Man
include Person
end

# Then the Man class have a function: age

########## Othe example
# File: functions.rb
module Functions
  def operation_a(a)
    a * 2
  end
  def operation_b(b)
    b * 10
  end
end

# File: main.rb
require 'functions'

# call operations
puts Functions.operation_a( 10 )
puts Functions.operation_a( 4 )

# But if i include the module
include Functions
puts operation_a( 10 )
puts operation_a( 4 )