.. role:: python(code)
   :language: python

.. index::
   dataclasses

Dataclasses
-----------

When working with classes, a lot of boiler-plate code is often required: 
always :python:`__init__, __repr__`, often :python:`__eq__, __lt__` for comparisons, 
often :python:`__hash__` when instances are used in sets or as dict keys, 
sometimes 'neutral representation' :python:`astuple, asdict` as an export interface. 
`Dataclasses <https://docs.python.org/3/library/dataclasses.html#>`_ does the job for you and are a huge time saver.



.. note::

   It seems at first glance that **class** attributes are defined. 
   However, this syntax in the context of a dataclass is called a ``field``. 
   It will actually create class instances with independent attributes. 
   To explicitly define a class attribute, the :python:`typing.ClassVar` type is required.


.. literalinclude:: ../../../../src/tools_methods/useful_modules/dataclasses_usage.py
   :name: dataclasses_usage
   :linenos:    
   :caption: dataclasses_usage