Is there a use for == or != in chained comparisons?

Question

I came across this question:

Why does the expression 0 < 0 == 0 return False in Python?

The answers make perfect sense once you understand chained comparisons in Python.

Chained comparisons allow you to write something like 0 < x < 100 which is very convenient for testing to see if something is between 0 and 100. But is there a case where it would even make sense to use == or != on either side of that comparison? 0 < x == 100 is equivalent to x == 100 for example.

Were == and != included in the chaining syntax just so that they wouldn't have to be exceptions to the rule, or is there an actual use case?

`x == y == z` is pretty clearly useful. (The one that causes the most problems is `in`.) — user2357112, Jan 10 '19 at 21:39
@user2357112 You should submit that as an answer, it makes perfect sense. — Mark Ransom, Jan 10 '19 at 21:41
Taking into account that all of the operators can be reimplemented and modified in behaviour there are virtually endless use-case for it. — Klaus D., Jan 10 '19 at 21:55

score 5 · Accepted Answer · answered Jan 10 '19 at 21:51

The most common use case for chaining == is chaining it with itself. x == y == z is a simple way to test that three things are all equal.

Using != in a comparison chain is also occasionally useful, but it tends to be less clear. 0 < x != 10 is more concise than 0 < x and x != 10, but the two comparisons don't feel quite as much like one big comparison as x == y == z does, and x != y != z is usually a mistake.

Is there a use for == or != in chained comparisons?

1 Answers1