작성한지 5년 이상 지난 게시물입니다. 최신의 정보와 맞지 않는 내용을 포함할 수도 있습니다.

I’ve been using a tuple as a substitution of a ternary operator in Python. Even though it is not exactly a ternary operator and has some drawbacks, but it works fine in most cases.

w = (u, v)[x < y]


When x < y is true, the whole expression of the tuple, (u, v)[x < y], will be evaluated as v because true means 1 here. Likewise, false will cause the tuple expression to be evaluated as u.

I had another trick to use with lambda functions.

lambda w: x < y and v or u


This might be a little less obvious to see what’s going on. When x < y is false, the following part, and v, will not be evaluated due to short-circuit evaluation, and it will jump to the next part, or u. Thus, this whole expression is to be evaluated as u. Similarly, when x < y is true, and v part has to be evaluated so it the whole expression will be evaluated as v.

However, as acute readers might already noticed, this trick has a major drawback. When v is a falsy value such as 0, False or None, the whole expression will be evaluated as u regardless of the result of x < y. So, one should refrain from using this trick unless it is impossible for v to be a falsy value.

Last Saturday, Cody told me that there is a ternary operator equivalent in Python.

w = v if x < y else u


Strictly speaking, it is not a ternary operator, rather an expression. But, in my opinion, it is more intuitive thus it makes it easier to maintain the code.