How to make a line break on the Python ternary operator?

Question

Sometimes a line containing a ternary operator in Python gets too long:

answer = \'Ten for that? You must be mad!\' if does_not_haggle(brian) else \"It\'s wo         


        

Answer 1

Bear in mind this advice from The Zen of Python: "Readability counts."

The ternary operator is most readable when it is all on one line.

x = y if z else w

When your conditions or variables push the line past 79 characters (see PEP8), readability begins to suffer. (Readability is also why dict/list comprehensions are best kept short.)

So, rather than trying to break the line using parentheses, you might find it is more readable if you convert it to a regular if block.

if does_not_haggle(brian):
    answer = 'Ten for that? You must be mad!'
else:
    answer = "It's worth ten if it's worth a shekel."

BONUS: The above refactoring reveals another readability issue: does_not_haggle is inverted logic. This would be even more readable, if you can rewrite the function:

if haggles(brian):
    answer = "It's worth ten if it's worth a shekel."
else:
    answer = 'Ten for that? You must be mad!'