Why am I getting a syntax error with this python ternary expression?

Question

Why am I getting a syntax error with this python ternary expression? Can't find anything in the documentation to say this is bad

right_pointer -= 1 if condition else left_pointer += 1

Answer 1

This is not a good way to code, but if you want a one-liner:

(right_pointer := right_pointer - 1) if condition else (left_pointer := left_pointer + 1)

This uses the walrus operator, which is in Python 3.8+.

But using a normal if/else is recommended:

if condition:
    right_pointer -= 1
else:
    left_pointer += 1

As Chepner says in his answer, you can't use statements in the conditional expression, only expressions