I humbly disagree that any of what you wrote is "obvious". On Fri, Feb 11, 2022 at 4:41 AM Steven D'Aprano <st...@pearwood.info> wrote:
> On Thu, Feb 10, 2022 at 02:27:42PM -0800, Neil Girdhar wrote: > > > AttributeError: can't set attribute 'f' > > > > This can be a pain to debug when the property is buried in a base class. > > > Would it make sense to mention the reason why the attribute can't be > set, > > namely that it's on a property without a setter? > > I have no objection to changing the error message, I'm sure it's a small > enough change that you should just open a ticket on b.p.o. for it. But I > don't expect that it will be particularly useful either. > > If you can't set an attribute on an object, aren't there three obvious > causes to check? > > - the object has no __dict__, and so has no attributes at all; > e.g. trying to set an attribute on a float; > > - the object has slots, but 'f' is not one of them; > > - or 'f' is a property with no setter (or a setter that raises > AttributeError). > > Have I missed any common cases? > > The error messages are different in each case, but even if they were the > same, there are three obvious causes to check, and property is one of > them. > > I suppose that there are exotic failures that could happen in > __getattribute__ or weird descriptors, or metaclass magic, etc, and > *those* might be hard to debug, but it doesn't seem likely to me that a > read-only property will be mysterious. > > Especially if you have the object available in the interactive > interpreter, so you can inspect it with the various tools available: > > * dir(obj) > * help(obj) > * type(obj).f # Will display <property object at 0x...> > > etc. Its hard to keep the existence of a property secret in Python. > > So once you know that f is a property, it might be hard to work out > which of the fifty-seven superclasses and mixins it came from *wink* but > that's neither here nor there :-) > > Maybe reporting "can't set property 'f'" is good enough. > > > -- > Steve > _______________________________________________ > 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/Z2AWWETWB72CKARR4DAHB3A2LFRLQR7X/ > Code of Conduct: http://python.org/psf/codeofconduct/ > > -- > > --- > You received this message because you are subscribed to a topic in the > Google Groups "python-ideas" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/python-ideas/IMzPQhK64lw/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > python-ideas+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/python-ideas/20220211093720.GO16660%40ando.pearwood.info > . >
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