R. David Murray <rdmurray@bitdance.com> added the comment: Yes, that's the way it works (and is intended to work, for performance reasons). The documentation on this could be improved...while it does say globals must be a dict and that locals can be any mapping object, it does it in a sentence that is a bit confusing in this context, and it doesn't make it clear that it has to be a "real" dict, not a subclass. (I wouldn't be surprised if that sentence was written back when you couldn't subclass dict.) ---------- assignee: -> docs@python components: +Documentation nosy: +docs@python, r.david.murray versions: +Python 3.7 -Python 3.5 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue31968> _______________________________________