python ? (conditional/ternary) operator for assignments [duplicate]

问题

C and many other languages have a conditional (aka ternary) operator. This allows you to make very terse choices between two values based on the truth of a condition, which makes expressions, including assignments, very concise.

I miss this because I find that my code has lots of conditional assignments that take four lines in Python:

if condition:
    var = something
else:
    var = something_else

Whereas in C it'd be:

var = condition? something: something_else;

Once or twice in a file is fine, but if you have lots of conditional assignments the number of lines explode and, worst of all, the eye is drawn to them.

I like the terseness of the conditional operator because it keeps things I deem un-strategic from distracting me when skimming the code.

So, in Python, are there any tricks you can use to get the assignment onto a single line to approximate the advantages of the conditional operator as I outlined them?

回答1:

Python has such an operator:

variable = something if condition else something_else

Alternatively, although not recommended (see @karadoc's comment):

variable = (condition and something) or something_else

回答2:

In older Python code, you may see the trick:

condition and something or something_else

however, this has been superseded by the vastly superior ... if ... else ... construct:

something if condition else something_else

来源：https://stackoverflow.com/questions/3091316/python-conditional-ternary-operator-for-assignments

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