On Mon, 15 May 2017 at 08:30 Guido van Rossum <gu...@python.org> wrote:
> This should be worked into a PEP, instead of living on as a bunch of > python-ideas posts and blogs. > > I find the attrs documentation (and Glyph's blog post about it) almost > unreadable because of the exalted language -- half the doc seems to be > *selling* the library more than *explaining* it. If this style were to > become common I would find it a disturbing trend. > > But having something alongside NamedTuple that helps you declare classes > with mutable attributes using the new PEP 526 syntax (and maybe a few > variants) would definitely be useful. Will someone please write a PEP? Very > few of the specifics of attrs need be retained (its punny naming choices > are too much for the stdlib). > In case someone decides to take this on, I wrote a blog post back in March that shows how to use __init_subclass__() to do a rough approximation of what Guido is suggesting: https://snarky.ca/customizing-class-creation-in-python/ . Based on my thinking on the topic while writing my blog post, the tricky bit is going to be deciding how to handle default values (i.e. if you set a default value like `attr: int = 42` on the class definition then you have `cls.attr` exist which might not be what you want if you would rather have the default value explicitly set on every instance but not fall through to the class (e.g. `del ins.attr; ins.attr` raises an AttributeError instead of falling through to `cls.attr`). You could remove the default from the class in your __init_subclass__(), but then you have to decide if that's too unexpected/magical for someone looking at the code. And I too would be interested in seeing something like this, if for any other reason than to help people not to misuse NamedTuple for quick-and-dirty data objects in new APIs (NamedTuple is meant to help move old-style tuple-based APIs to a class-based one). -Brett > > --Guido > > On Mon, May 15, 2017 at 4:05 AM, Nick Coghlan <ncogh...@gmail.com> wrote: > >> On 14 May 2017 at 17:12, Abdur-Rahmaan Janhangeer <arj.pyt...@gmail.com> >> wrote: >> > Whatever you all propose, >> > >> > coming from a java and c++ background, OOP in python is quite >> cumbersome. >> > >> > if you tell that i am not a python guy, then consider that current oop >> style >> > does not reflect python's style of ease and simplicity >> > >> > is __init__ really a good syntax choice? >> >> That's a different question, and one with a well-structured third >> party solution: https://attrs.readthedocs.io/en/stable/ >> >> See https://mail.python.org/pipermail/python-ideas/2017-April/045514.html >> for some ideas on how something like attrs might be adapted to provide >> better standard library tooling for more concise and readable class >> definitions. >> >> Cheers, >> Nick. >> >> -- >> Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia >> _______________________________________________ >> Python-ideas mailing list >> Python-ideas@python.org >> https://mail.python.org/mailman/listinfo/python-ideas >> Code of Conduct: http://python.org/psf/codeofconduct/ >> > > > > -- > --Guido van Rossum (python.org/~guido) > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ >
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