It seems all the core devs who have commented on this are in the positive (Victor, Yury, Ethan, Yury, Guido, Terry, and Steven; MAL didn't explicitly vote). So to me that suggests there's enough support to warrant writing a PEP. Are you up for writing it, Victor, or is someone else going to write it?
On Tue, 28 Feb 2017 at 13:18 Victor Stinner <victor.stin...@gmail.com> wrote: > Hi, > > For technical reasons, many functions of the Python standard libraries > implemented in C have positional-only parameters. Example: > ------- > $ ./python > Python 3.7.0a0 (default, Feb 25 2017, 04:30:32) > >>> help(str.replace) > replace(self, old, new, count=-1, /) # <== notice "/" at the end > ... > >>> "a".replace("x", "y") # ok > 'a' > > >>> "a".replace(old="x", new="y") # ERR! > TypeError: replace() takes at least 2 arguments (0 given) > ------- > > When converting the methods of the builtin str type to the internal > "Argument Clinic" tool (tool to generate the function signature, > function docstring and the code to parse arguments in C), I asked if > we should add support for keyword arguments in str.replace(). The > answer was quick: no! It's a deliberate design choice. > > Quote of Yury Selivanov's message: > """ > I think Guido explicitly stated that he doesn't like the idea to > always allow keyword arguments for all methods. I.e. `str.find('aaa')` > just reads better than `str.find(needle='aaa')`. Essentially, the idea > is that for most of the builtins that accept one or two arguments, > positional-only parameters are better. > """ > http://bugs.python.org/issue29286#msg285578 > > I just noticed a module on PyPI to implement this behaviour on Python > functions: > > https://pypi.python.org/pypi/positional > > My question is: would it make sense to implement this feature in > Python directly? If yes, what should be the syntax? Use "/" marker? > Use the @positional() decorator? > > Do you see concrete cases where it's a deliberate choice to deny > passing arguments as keywords? > > Don't you like writing int(x="123") instead of int("123")? :-) (I know > that Serhiy Storshake hates the name of the "x" parameter of the int > constructor ;-)) > > By the way, I read that "/" marker is unknown by almost all Python > developers, and [...] syntax should be preferred, but > inspect.signature() doesn't support this syntax. Maybe we should fix > signature() and use [...] format instead? > > Replace "replace(self, old, new, count=-1, /)" with "replace(self, > old, new[, count=-1])" (or maybe even not document the default > value?). > > Python 3.5 help (docstring) uses "S.replace(old, new[, count])". > > Victor > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ >
_______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/