[Python-Dev] assignment expressions: an alternative proposal (original) (raw)

Steven D'Aprano steve at pearwood.info
Tue Apr 24 11:34:43 EDT 2018

On Tue, Apr 24, 2018 at 11:05:57AM -0400, Yury Selivanov wrote:

Well, myfunc(a=(b:=foo)) or myfunc(b:=foo) are also barely readable to my eye.

There's no advantage to using binding-expressions unless you're going to re-use the name you just defined, and that re-use will give you a hint as to what is happening:

my_func(arg, buffer=(buf := [None]*get_size()), size=len(buf))

My expectation is that users won't use any form of assignment expressions in function calls, it's painful with both proposals.

If binding-expressions are accepted into the language, I will certainly use them in function calls, if and when appropriate. I don't expect it will be common, but I'm sure it will happen.

-- Steve

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