On 12/07/2017 11:46 AM, Paul Moore wrote:
On 7 December 2017 at 18:28, Ethan Furman <et...@stoneleaf.us> wrote:
The simple answer is No, and all the answers agree on that point.
It does beg the question of what an identity function is, though.
My contention is that an identity function is a do-nothing function that
simply returns what it was given:
--> identity(1)
1
--> identity('spam')
'spam'
--> identity('spam', 'eggs', 7)
('spam', 'eggs', 7)
Of the five answers to that SO question, mine is the only one that will
correctly handle those three examples. If you agree with my contention feel
free to up-vote my answer. :)
IMO (as a mathematician ;-)) the identity function is a
*single-argument* function that returns the value passed to it. So:
def identity(x):
return x
See https://en.wikipedia.org/wiki/Identity_function
identity(1,2) is an error.
Extending the definition to multiple arguments causes all sorts of
confusion, as you've seen.
So in other words:
for thing in (
1,
(2, 3),
'spam',
('eggs', 'green', 4.15),
(1, ),
):
assert thing == identity(thing)
try:
identity('too', 'many', 'things')
except TypeError:
pass
else:
raise Exception('identity should only be passed a single item')
Thank you for clearing that up, Paul!
I up-voted your answer, hopefully others will also:
https://stackoverflow.com/a/47702881/208880
--
~Ethan~
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