On 21 April 2018 at 07:33, Tim Peters <tim.pet...@gmail.com> wrote: > I expected that, given that expressions "naturally nest", chained > targets could still be specified: > > a := b := c:= 5 > > but since they're all plain names there's no way to tell whether the > bindings occur "left to right" or "right to left" short of staring at > the generated code.
The fact class namespaces are ordered by default now allow us to demonstrate the order of multiple target assignments and tuple unpacking without staring at generated code: >>> class AssignmentOrder: ... a = b = c = 0 ... d, e, f = range(3) ... >>> class ReversedAssignmentOrder: ... c = b = a = 0 ... f, e, d = range(3) ... >>> [attr for attr in AssignmentOrder.__dict__ if not attr.startswith("_")] ['a', 'b', 'c', 'd', 'e', 'f'] >>> [attr for attr in ReversedAssignmentOrder.__dict__ if not >>> attr.startswith("_")] ['c', 'b', 'a', 'f', 'e', 'd'] So that's a situation where "name = alias = value" could end up matching "alias := name := value" (Even in earlier versions, you can illustrate the same assignment ordering behaviour with the enum module, and there it makes even more of a difference, as it affects which name binding is considered the canonical name, and which are considered aliases). Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ 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/archive%40mail-archive.com