On Tue, 21 Apr 2015 at 09:59 Cory Benfield <c...@lukasa.co.uk> wrote: [...]
> Further, Python's type system is not sufficiently flexible to allow > library authors to adequately specify the types their code actually > works on. I need to be able to talk about interfaces, because > interfaces are the contract around which APIs are build in Python, but > I cannot do that with this system in a way that makes any sense at > all. To even begin to be useful for library authors this PEP would > need to allow some kind of type hierarchy that is *not* defined by > inheritance, but instead by interfaces. We've been discouraging use of > 'type' and 'isinstance' for years because they break duck typing, but > that has *nothing* on what this PEP appears to do to duck typing. > > This is why I feel like this PEP may be a real threat to duck typing. If people constantly get told by their editor / IDE that they are calling function with the wrong argument types, what are they going to do? They may start adopting the same approach as in Java / C++ etc... where interfaces must be explicitly defined and the practice of duck typing may become forgotten because discouraged by the tools programmers use. I guess what I'm saying is that this could encourage a very significant cultural change in the way Python code is written towards a less flexible mindset. -- Arnaud
_______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
