Does Python have a ternary conditional operator?

Question

If Python does not have a ternary conditional operator, is it possible to simulate one using other language constructs?

Answer 1

Hello!

Python does have a ternary conditional operator. Consider the case where you would normally write this:

if condition:

x = true_body

else:

x = false_body

You can always instead write this:

x = true_body if condition else false_body

true_body will only be evaluated if condition is true; likewise, false_body will only be evaluated if condition is false. These are the same rules C uses for its equivalent language construct:

x = condition ? true : false

Many Python programmers use a dictionary literal for more complicated versions of this situation -- such as this one where the programmer has to distinguish between three options and a default value:

word = "cinnamon"

next_word = {

"cherry": "cola",

"apple": "turnover",

"mud": "pie",

}.get(choice, "bun")

# next_word now == "bun"

However, be cautioned that in the dictionary literal solution, Python evaluates every item. In other words:

# == this code will complete with "delicious!" so long as `choice` != "bomb"

x = (

"delicious!" if choice == "candycane" else

1/0 if choice == "bomb" else

"beats me"

)

# == this code will always crash with a ZeroDivisionError ==

x = {

"candycane": "delicious!",

"bomb": 1/0

}.get(choice, "beats me")