STY: Document line change bump to 88 char

Author: ksunden

doc/api/next_api_changes/development/24893-KS.rst

@@ -0,0 +1,15 @@
+Maximum line length increased to 88 characters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The maximum line length for new contributions has been extended from 79 characters to
+88 characters.
+This change provides an extra 9 characters to allow code which is a single idea to fit
+on fewer lines (often a single line).
+Other line lengths considered included 115 and 99, but ultimately 88 characters was the
+consensus as it is relatively conservative while still providing reasonable benefit.
+The ability to view side-by-side git diffs was a key point in choosing the smaller
+limit.
+Additionally, it is easier to increase the line length again than to decrease it if it
+was found too large.
+The chosen length is the same as `black <https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#line-length>`_.
+Their justifications influenced the discussion and provided a standard value.

doc/devel/coding_guide.rst

@@ -30,7 +30,8 @@ rules before submitting a pull request:
   for more details.
 
 * Formatting should follow the recommendations of PEP8_, as enforced by
-  flake8_.  You can check flake8 compliance from the command line with ::
+  flake8_. Matplotlib modifies PEP8 to extend the maximum line length to 88
+  characters. You can check flake8 compliance from the command line with ::
 
     python -m pip install flake8
     flake8 /path/to/module.py
@@ -156,6 +157,12 @@ Content topics:
 * Does the PR conform with the :ref:`coding_guidelines`?
 * Is the :ref:`documentation <pr-documentation>` (docstrings, examples,
   what's new, API changes) updated?
+* Is the change only reflowing code/docstrings for increased line length?
+  Generally, such changes are discouraged when not part of other non-stylistic
+  work because it obscures the git history of functional changes to the code.
+  Reflowing a method or docstring as part of a larger refactor/rewrite is
+  acceptable.
+
 
 Organizational topics: