Long Parameter List
=========================================

Given following class `Order`:

.. code-block:: python

   class Order:
      _id: str
      _customer_id: str
      _customer_address: str
      _has_priority: bool
      _product_ids: list[str]

      def __init__(
         self,
         id: str,
         customer_id: str,
         customer_address: str,
         product_ids: list[str],
         is_premium_customer: bool,
      ) -> None:
         self._id = id
         self._customer_id = customer_id
         self._customer_address = customer_address
         self._product_ids = product_ids.copy()
         self._has_priority = is_premium_customer

      def get_product_ids(self):
         return self._product_ids

      def get_customer_id(self) -> str:
         return self._customer_id


Issues
------------

Make `id` parameter optional
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This would require moving the parameter to the end breaking all client code.

Knowing too much
~~~~~~~~~~~~~~~~~~

Initializer receives a set of arguments which characterize customer.
This introduces strong coupling between customer details and order.
What if we need to add another customer attribute?

This would break all client code.

Parameter order
~~~~~~~~~~~~~~~~~~~

Because the list of parameters is more than 2-3, it is very likely the client code
to pass parameters in wrong order.

.. collapse:: Solution 1

   One possible approach is to make all parameters keyword parameters, by specifying asterisk
   '*' after the `self` parameter. This will force the client code to always pass keyword arguments.

   Further to address the knowledge about customer we create a Customer class and replace all
   customer-related parameters with a single parameter `customer`.

   .. code-block:: python
      :linenos:

      from dataclasses import dataclass
      from uuid import uuid4

      @dataclass
      class Customer:
         id: str
         address: str
         has_premium_subscription: bool = False

      class Order:
         _id: str
         _customer: Customer
         _product_ids: list[str]

         def __init__(
            self,
            *,
            customer: Customer,
            product_ids: list[str],
            id: str = None
         ) -> None:
            self._id = id | uuid4()
            self._customer = customer
            self._product_ids = product_ids.copy()

         def get_product_ids(self):
            return self._product_ids

         def get_customer_id(self) -> str:
            return self._customer_id