Movatterモバイル変換

[Python-ideas] Fwd: Define a method or function attribute outside of a class with the dot operator

• Previous message (by thread):[Python-ideas] Fwd: Define a method or function attribute outside of a class with the dot operator
• Next message (by thread):[Python-ideas] Fwd: Define a method or function attribute outside of a class with the dot operator
• Messages sorted by:[ date ][ thread ][ subject ][ author ]

One thing that I don't think has been mentioned, but that brings me froma +0 to a more negative outlook, is the interaction between this proposaland some of python's existing class-related features, metaclasses anddescriptors. That is currently we know that function definition, and evenmethod definition, will not have side effects. This potentially changesthat since    def Foo.foo(self):        ...could be a descriptor. Even if it doesn't, its possible that `Foo.foo` isactually resolved from `Foo._foo`, and so this potentially further confusesthe naming considerations.Then we have metaclasses. Prior to this change, it would be fully themonkeypatcher's responsibility to do any metaclass level changes if theywere necessary when monkeypatching. However, since we are potentiallyadding a first class support for certain monkeypatches, It raises aquestion about some first class way to handle monkeypatched methods. Do weneed to provide some kind of method to a metaclass writer that allows themto handle methods that are patched on later? Or does the language stillignore it?--JoshOn Fri, Feb 10, 2017 at 12:20 PM Nick Coghlan <ncoghlan at gmail.com> wrote:> On 10 February 2017 at 16:25, Steven D'Aprano <steve at pearwood.info> wrote:> > On Sat, Feb 11, 2017 at 01:25:40AM +1100, Chris Angelico wrote:> >> >> For what it's worth, my answers would be:> >>> >> __name__ would be the textual representation of exactly what you typed> >> between "def" and the open parenthesis. __qualname__ would be built> >> the exact same way it currently is, based on that __name__.> >> > If I'm reading this right, you want this behaviour:> >> > class Spam:> >     pass> >> > def Spam.func(self): pass> >> > assert 'Spam.func' not in Spam.__dict__> > assert 'func' in Spam.__dict__> >> > assert Spam.func.__name__ == 'Spam.func'> > assert Spam.func.__qualname__ == 'Spam.Spam.func'> >> > If that's the case, I can only ask... what advantage do you see from> > this? Because I can see plenty of opportunity for confusion, and no> > advantage.>> What I would personally hope to see from the proposal is that given:>>     class Spam:>         pass>>     def Spam.func(self):>         return __class__>> the effective runtime behaviour would be semantically identical to:>>     class Spam:>         def func(self):>             return __class__>> such that:>>   * __name__ is set based on the method name after the dot>   * __qualname__ is set based on the __name__ of the given class>   * __set_owner__ is called after any function decorators are applied>   * zero-argument super() and other __class__ references work properly> from the injected method>> Potentially, RuntimeError could be raised if the reference before the> dot is not to a type instance.>> If it *doesn't* do that, then I'd be -1 on the proposal, since it> doesn't add enough expressiveness to the language to be worth the> extra syntax. By contrast, if it *does* do it, then it makes class> definitions more decomposable, by providing post-definition access to> parts of the machinery that are currently only accessible during the> process of defining the class.>> The use case would be to make it easier to inject descriptors when> writing class decorators such that they behave essentially the same as> they do when defined in the class body:>>     def my_class_decorator(cls):>         def cls.injected_method(self):>             # Just write injected methods the same way you would in a> class body>             return __class__>         return cls>> (Actually doing this may require elevating super and __class__ to true> keyword expressions, rather than the pseudo-keywords they are now)>> Cheers,> Nick.>> --> Nick Coghlan   |ncoghlan at gmail.com   |   Brisbane, Australia> _______________________________________________> Python-ideas mailing list>Python-ideas at python.org>https://mail.python.org/mailman/listinfo/python-ideas> Code of Conduct:http://python.org/psf/codeofconduct/>-------------- next part --------------An HTML attachment was scrubbed...URL: <http://mail.python.org/pipermail/python-ideas/attachments/20170210/461514df/attachment-0001.html>

• Previous message (by thread):[Python-ideas] Fwd: Define a method or function attribute outside of a class with the dot operator
• Next message (by thread):[Python-ideas] Fwd: Define a method or function attribute outside of a class with the dot operator
• Messages sorted by:[ date ][ thread ][ subject ][ author ]