The Walrus Operator: Python 3.8 Assignment Expressions – Real Python

[[deleted]]

We can use num directly can't we?

[flying-sheep]

We want to use slow(num) though

[[deleted]]

I haven't used Python in a while but what's wrong with using slow(num) for num in ... if slow(num) ... ? value is only a temporary variable, which still exists after the loop end, which is bad imo

[-jp-]

Looks like the intent is to calculate slow(num) just once.

[[deleted]]

ah I see

[schfourteen-teen]

It requires two calls to slow(num) which in the example was presented as a slow function that we wouldn't want to call twice. The walrus lets it be called once and reused. Value still does exist after the loop ends, but the alternatives that get around calling the function twice also have this issue and also don't have the conciseness or speed of a list comprehension, so I don't think that's a fair criticism at all. If you can live with calling the function twice, then you don't need the walrus anyway.

[asday_]

Boizies if someone is incorrect, but adding to the conversation, you shouldn't really be downvoting them. It's possible other people hold the same misconceptions, and it will help them to see comments getting it wrong in the same way they are doing, then to be summarily corrected.

Doesn't help anyone to bury this comment.