The way I recall it, we arrived at the perfect syntax (using ?) and semantics. The issue was purely strong hesitation about whether sprinkling ? all over your code is too ugly for Python, and in the end we couldn't get agreement on *that*. Another problem is PEP 505 -- it is full of discussion but its specification is unreadable due to the author's idea to defer the actual choice of operators and use a strange sequence of unicode characters instead.
If someone wants to write a new, *short* PEP that defers to PEP 505 for motivation etc. and just writes up the spec for the syntax and semantics we'll have a better starting point. IMO the key syntax is simply one for accessing attributes returning None instead of raising AttributeError, so that e.g. `foo?.bar?.baz` is roughly equivalent to `foo.bar.baz if (foo is not None and foo.bar is not None) else None`, except evaluating foo and foo.bar only once. On Sat, Sep 10, 2016 at 10:14 AM, Random832 <random...@fastmail.com> wrote: > On Sat, Sep 10, 2016, at 12:48, Stephen J. Turnbull wrote: >> I forget if Guido was very sympathetic to null-coalescing operators, >> given somebody came up with a good syntax. > > As I remember the discussion, I thought he'd more or less conceded on > the use of ? but there was disagreement on how to implement it that > never got resolved. Concerns like, you can't have a?.b return None > because then a?.b() isn't callable, unless you want to use a?.b?() for > this case, or some people wanted to have "a?" [where a is None] return a > magic object whose attribute/call/getitem would give no error, but that > would have to keep returning itself and never actually return None for > chained operators. > _______________________________________________ > 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/
