https://www.reddit.com/r/Python/comments/8vmq27/pep_572_assignment_expressions_is_officially/
XD nice feedbacks about the pep Abdur-Rahmaan Janhangeer https://github.com/Abdur-rahmaanJ On Wed, 4 Jul 2018, 06:02 Steven D'Aprano, < steve+comp.lang.pyt...@pearwood.info> wrote: > Congratulations to Chris Angelico for breaking the dreaded "any PEP > written by Chris will be rejected" curse :-) > > Guido has announced his intention to accept PEP 572 (assignment > expressions) once the PEP has been cleaned up a bit. > > https://www.python.org/dev/peps/pep-0572/ > > (The current version of the PEP doesn't quite match the proposal as > nutted out over about a bazillion emails on two mailing lists starting in > FEBRUARY!!!) > > > Summary: > > Python 3.8 will allow an assignment-as-expression operator. The most > common uses are expected to be if and while statements: > > condition = expression > while condition: > do_something() > condition = expression > > will become: > > while condition := expression: > do_something() > > > Cascades of if statements, such as: > > # the dreaded arrowhead anti-pattern > mo = re.match(pattern, text) > if mo: > ... > else: > mo = re.match(another_pattern, text): > if mo: > ... > else: > mo = re.match(third_pattern, text): > if mo: > ... > > > will become flatter and easier to read: > > if mo := re.match(pattern, text): > ... > elif mo := re.match(another_pattern, text): > ... > elif mo := re.match(third_pattern, text): > ... > > > FAQs: > > Q. Why Pascal's assignment operator := instead of regular = assignment? > > A. To avoid the C bug magnet of mistakenly writing "if x = expr" when > you intended to write "if x == expr". > > > Q. Why not use "as"? > > A. There is an ambiguity due to with and except statements: > > with expr as name > > except Exception as name > > are already permitted and mean something different to ordinary > assignment expressions. > > > Q. Oh no, Python is doomed! This is the end of the world! > > A. That's not actually a question, is it? > > > > > -- > Steven D'Aprano > "Ever since I learned about confirmation bias, I've been seeing > it everywhere." -- Jon Ronson > > -- > https://mail.python.org/mailman/listinfo/python-list > -- https://mail.python.org/mailman/listinfo/python-list
