Could you file an issue about this on bugs.python.org <http://bugs.python.org/>?
Ronald — Twitter / micro.blog: @ronaldoussoren Blog: https://blog.ronaldoussoren.net/ > On 13 Dec 2020, at 03:16, Ivo Shipkaliev <ivo.shipkal...@gmail.com> wrote: > > Hiya :) > > I'm recently working with tkinter and I noticed that: > > >>> import tkinter as tk > >>> string_var = tk.StringVar() > > is throwing an AttributeError: > > > Traceback (most recent call last): > > . . . > > File "...\lib\tkinter\__init__.py", line 505, in __init__ > > Variable.__init__(self, master, value, name) > > File "...\lib\tkinter\__init__.py", line 335, in __init__ > > self._root = master._root() > > AttributeError: 'NoneType' object has no attribute '_root' > > ... which is making me question myself: > -- "Why am I looking for a '_root' attribute on a NoneType object here?", or > -- "How did I end up with a NoneType, to be searched for a '_root' attribute > in the first place?" > I have done something wrong or I don't know something apparently. > > Following the traceback, looking at "tkinter\__init__.py", lines 333-335 > leads us to the implementation of StringVar's parent: class Variable: > > 333 > if not master: > 334 > master = _default_root > 335 > self._root = master._root() > > Class Variable constructor interface: > > 317 > def __init__(self, master=None, value=None, name=None): > > Clearly, on line 335, we are relying on the "master" to have a "_root" > callable. If "master" was not declared upon class instantiation (line 317), a > value can come from _default_root, which is a global module variable. > _default_root is holding a Tk instance, if one was instantiated. So, if > neither "master" nor _default_root was defined, line 335 will result in an > AttributeError. > > Now, would it be a good idea if we keep the user better informed by making > the aforementioned lines look something like?: > > 333 > if not master: > 334 > master = _default_root > 335 > if not master: > 336 > raise RuntimeError(f"{self.__class__.__name__!r}: > 'master' must be defined or a Tk instance must be present!") > 337 > self._root = master._root() > > ... and not relying on this inexplicable AttributeError. > > Thank you for your time! > > Regards > Ivo Shipkaliev > _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/FSQUFJJQDNSRN4HI7VFXWCNO46YLXQDS/ > Code of Conduct: http://python.org/psf/codeofconduct/
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