Linters introduction
====================

The Karen mode
--------------

Most linters bring along recommended configurations or rules. Usually this includes only a subset of all available rules, and a lot will be deactivated by default. You can also call this **whitelisting**, since only a selected set of rules is activated.

However, we don't want that behaviour. We want the linter to complain about every possible violation, i.e. set it in **Karen Mode**. Instead of **whitelisting** rules, we want **blacklist** or customise rules we don't like. This means we're activating all rules by default and start overwriting the ones we don't like.

Common rules
------------

There are some common rules which are valid throughout all different programming languages and linters.

Line length
~~~~~~~~~~~

The maximum line length is always set to **100 characters**.

Indentation
~~~~~~~~~~~

We usually **use 4 spaces** and we **never use tabs** to indent code, regardless of the `file size <https://www.youtube.com/watch?v=SsoOG6ZeyUI>`_.

.. hint::

    Of course there are exceptions for files which are picky about the number of spaces or tabs, such as a  ``Makefile``.
 
.. important::

    For **YAML** we make an exception of **2 spaces**, due to the indentation for objects / dicts in lists. YAML is always consistent & valid w/ 2 spaces. With **4 spaces**, it has either inconsistent whitespaces or invalid syntax, as they're mutually exclusive:

    .. code-block:: yaml

        # CORRECT: Consistent spaces (2), valid syntax

          object:
            - foo: 'Foo' 
              bar: 'Bar' # <-- correct indentation, correct amount of spaces
        # ^^
        # 12^^
        #   12


        # INCORRECT: Consistent spaces (4), invalid syntax
        
          object:
              - foo: 'Foo' 
                  bar: 'Bar' # <-- wrong indentation, correct amount of spaces
        # ^^^^
        # 1234^^^^
        #     1234


        # INCORRECT: Inconsistent spaces (2 & 4), valid syntax
        
          object:
              - foo: 'Foo' 
                bar: 'Bar' # <-- correct indentation, incorrect amount of spaces
        # ^^^^
        # 1234^^
        #     12

Variable assignment alignment
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Readability counts and thus variable assignments can / should be aligned like this:

.. code-block:: python

    short_var       = 'example'
    longer_var      = 'example'
    a_very_long_var = 'example'