On Thu, Jul 19, 2018 at 5:45 PM, Brice Parent <cont...@brice.xyz> wrote: > The biggest drawback of this, is that (if I understand it well), it may be > done quite easily without any change to the language: > > def first_set(*elements): # please don't mind the name of the function, > it's not the purpose here > """ Will return the first element that is not None """ > for element in elements: > if element is not None: > return element > > raise AllNoneException() > > first_set(3, 5) # -> 3 > first_set(None, 5) # -> 5 > first_set(None, None, 8, 10) # -> 8 > first_set(None, Car(model="sport")).buy() # calling > Car(model="sport").buy() > first_set(None, ["a", "b", "c"])[1] # -> "b" > first_set(None, None) # -> exception is raised > > (note that such function could even accept a "rejected_values" kwarg, like > `rejected_values=(None, [], "")`, just by replacing the `if` clause by `if > element not in rejected_values:`)
No it can't, for the same reason that the 'and' and 'or' operators can't be implemented cleanly as functions: it short-circuits. The right-hand operator _will not_ be evaluated unless the left is None. ChrisA _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
