Make stem formatting parameters keyword only.

This will allow to simplify the implementation because, currently, `stem(*args, linefmt=None, ...)` still tries to resolve excess positionally passed args, to *linefmt* and following parameters, which is quite a bit of logic. OTOH, since we have 3 formats, passing them positionally is already difficult from a usability/readability perspective, because they can easily be mixed up.
matplotlib · Sep 19, 2021 · 07cbdfc · 07cbdfc
1 parent c53216b
commit 07cbdfc
Show file tree

Hide file tree

Showing 2 changed files with 3 additions and 0 deletions.
diff --git a/doc/api/next_api_changes/deprecations/21126-TH.rst b/doc/api/next_api_changes/deprecations/21126-TH.rst
@@ -0,0 +1,2 @@
+Passing formatting parameters positionally to ``stem()`` is deprecated
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -2773,6 +2773,7 @@ def broken_barh(self, xranges, yrange, **kwargs):
 
         return col
 
+    @_api.make_keyword_only("3.5", 'linefmt')
     @_preprocess_data()
     def stem(self, *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
              label=None, use_line_collection=True, orientation='vertical'):