Python Ternary Operator – Understanding Behavior

pythonternary-operator

when I evaluate the following operation

0 if True else 1 + 1 if False else 1

it evaluates to 0 however when I write with brackets like

( 0 if True else 1 ) + ( 0 if False else 1 )

it evaluates correctly to 1 , what is happening in the first case.

0 if True else 1 + 1 if False else 1

is actually:

(0) if (True) else ((1 + 1) if (False) else (1))

which is definitely differs from what you want:

((0) if (True) else (1)) + ((1) if (False) else (1))

The conditional operator in Python is used for expressions only, but assignments are statements. You can use

q = d.setdefault(x, {})

to get the desired effect in this case. See also the documentation of dict.setdefault().