module example

module_example.rb

# Module.rb
module Account
  def default_attributes
    super.merge(common_attributes)
  end

  def common_attributes
    {
      name: '',
      state: '',
      city: ''
    }
  end
end

# Account.rb
class AccountUser
  include Account
  def default_attributes
    {
      cpf: ''
    }
  end
end

# AccountStore
class AccountStore
  include Account
  def default_attributes
    { 
      cnpj: ''
    }
  end
end

# Note que AccountUser fica antes de Account
AccountUser.ancestors.
=> [AccountStore, Account, Object, Kernel, BasicObject]

AccountUser.new.default_attributes
=> {:cnpj=>""}

AccountUser.new.common_attributes
=> {:name=>"", :state=>"", :city=>""}