Le 19/07/2018 à 10:36, Chris Angelico a écrit :
On Thu, Jul 19, 2018 at 5:45 PM, Brice Parent <contact@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 Thanks for the clarification, I didn't think about that.
It doesn't make it beautiful or easily readable, but at least, I understand how it may be useful then!