Steven Turnbull wrote:
Christoph Groth writes:
Wouldn't it be a pity not to liberate assignments from their boring statement existence?
Maybe not. While it would be nice to solve the loop-and-a-half "problem" and the loop variable initialization "problem" (not everyone agrees these are even problems, especially now that we have comprehensions and generator expressions), as a matter of taste I like the fact that this particular class of side effects is given weighty statement syntax rather than more lightweight expression syntax.
I think that this is the crucial point. If it is indeed a design principle of Python that expressions should not have the side-effect of assigning names, than the whole discussion of PEP 572 could have been stopped early on. I didn't have this impression since core devs participated constructively in the discussion.
That is, I find statement syntax more readable.
Many people will agree that := is more readable when used in cases where it's meant to be used (as listed in the PEP). Your objection seems to refer to the potential for "clever" misuse, like i := (a := list(iterator)).index(elem) instead of a := list(iterator) i := a.index(elem) I think that the ":=" syntax catches the eye and makes it easy to spot even hidden assignment expressions that shouldn't have been used. Note that the proposed syntax can be actually *more* readable even when used as a statement, like in equal := a == b Personally, I even slightly prefer a := 3 to the commonplace a = 3 because it visually expresses the asymmetry of the operation. (And no, Turbo Pascal was not my first programming language. :-) Christoph