A very emotional appeal, you don't seem to grasp the usability improvements this will give. I hear you but at this point appeals to Python's "Zen" don't help you.
On Wed, Apr 25, 2018 at 1:21 PM, Łukasz Langa <luk...@langa.pl> wrote: > PEP 572 caused a strong emotional reaction in me. I wanted to first > understand > my intuitive objection to the idea before posting anything. > > I feel that (name := expression) doesn't fit the narrative of PEP 20. It > doesn't remove complexity, it only moves it. What was its own assignment > before > now is part of the logic test. This saves on vertical whitespace but makes > parsing and understanding logic tests harder. This is a bad bargain: logic > tests already contain a lot of complexity that human readers have to cope > with. > > Proponents of := argue it makes several patterns flatter (= better than > nested) > to express. Serial regular expression matching is a popular example. > However, > (name := expression) itself is making logic tests more nested, not > flatter. It > makes information in the logic test denser (= worse than sparse). Since it > also > requires an additional pair of parentheses, it forces the reader to > decompose > the expression in their head. > > := also goes against having one obvious way to do it. Since it's an > expression, > it can also be placed on its own line or in otherwise weird places like > function call arguments. I anticipate PEP 8 would have to be extended to > explicitly discourage such abuse. Linters would grow rules against it. > This is > noise. > > I'm -1 on PEP 572, I think it's very similar in spirit to the rejected PEP > 463. > > -- Ł > > > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: https://mail.python.org/mailman/options/python-dev/ > guido%40python.org > > -- --Guido van Rossum (python.org/~guido)
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