Bug report

In matplotlib v3.1.1, the font_manager.FontManager.score_weight function was made more robust, and now issues an exception if a integer value is passed as a string (e.g. '500').

This, however, causes havoc with my custom style sheet, in which I define font.weight: 500, which then appears to be converted to '500' by the time it reaches the score_weight function.

Expected outcome

Specifying font.weight: 500 used to work in earlier versions. The doc still suggests (indirectly) that this should work.

Question
What is the proper way to specify integer font weights in style sheets ? Should they be banned (and the doc clarified) in favor of name-based strings (e.g. normal) ? Or the score_weight function modified to handle them?

Matplotlib version

• Operating system: OS X 10.13.6
• Matplotlib version: 3.1.1
• Python version: 3.7.3