There seems to be a major misunderstanding here. A None-coalescing operator is not for catching AttributeError, it's a shortcut similar to "a or b" except that it checks for "a is None" rather than bool(a).
On Sat, Sep 10, 2016 at 4:38 PM, David Mertz <me...@gnosis.cx> wrote: > Sorry, I sent this accidentally as private reply, then tried to fix it on > phone. The latter produced horrible formatting. Please just read this > version. > > On Sat, Sep 10, 2016 at 4:10 PM, Guido van Rossum <gu...@python.org> wrote: >> >> So you're offering `NoneCoalesce(x).bar` as less-ugly alternative to >> `x?.bar`... Color me unconvinced. > > > No, I'm offering a more realistic use pattern: > > for x in get_stuff(): > > x = NoneCoalesce(x) > > # ... bunch of stuff with x ... > # ... more stuff with nested keys or attributes ... > > x2 = x.foo > > x3 = x.bar.baz[x2] > > x4 = x(x.val) > > result = x3(x4) > > > > As a less ugly alternative in the fairly uncommon case that you want None > coalescing as the behavior of getting attributes, keys, call values, etc. > that may or may not be available (AND where you don't want to wrap all of > those access patterns in one try/except block). > > In contrast, the ugly version of even this pretty simple toy code with the > hypothetical syntax would be: > > for x in get_stuff(): > > # ... bunch of stuff with x ... > > # ... more stuff with nested keys or attributes ... > > x2 = x?.foo > > x3 = x?.bar?.baz?[x2] > > x4 = x?(x?.val) > > result = x3?(x4) > > > This second case looks absolutely awful to me. And real world uses, if > implemented, would quickly get much worse than that. > > Yours, David... > > -- > Keeping medicines from the bloodstreams of the sick; food > from the bellies of the hungry; books from the hands of the > uneducated; technology from the underdeveloped; and putting > advocates of freedom in prisons. Intellectual property is > to the 21st century what the slave trade was to the 16th. > > > > -- > Keeping medicines from the bloodstreams of the sick; food > from the bellies of the hungry; books from the hands of the > uneducated; technology from the underdeveloped; and putting > advocates of freedom in prisons. Intellectual property is > to the 21st century what the slave trade was to the 16th. > > _______________________________________________ > 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/
