On Tue, Apr 24, 2018 at 11:03:35AM -0400, Yury Selivanov wrote: > My point was that when you see lots of '=' and ':=' used at the > statement level, one might try to write "if x = 1" instead of "if x := > 1" -- boom, we have an unexpected SyntaxError for some users.
That's a *good* thing. They will then learn not to write x = 1 as an expression. Also, if I write lots of x := 1 binding-expressions as statements, my code is bad and deserves to fail code-review. But why would I write the extra colon (one character, two key-presses) to use x := 1 as a statement, when x = 1 will work? That's a sure sign that I don't know what I'm doing. (Or that I desperately wish I was writing Pascal.) I don't think we need worry about this. The sort of code that is filled with binding-expressions used as statements will almost certainly be so un-Pythonic and ugly in many other ways, that this won't make any difference. > In my opinion adding *any* assignment expression syntax to Python > *will* create this sort of issues. PEP 572 isn't free of them, my > proposal isn't free of them. My proposal doesn't add a new ':=' > operator at the cost of slightly complicating rules around '='. PEP > 572 avoids complicating '=', but adds an entirely new form of > assignment. Indeed. That is true: either way, we introduce complexity into the language. (But that will allow us to reduce complexity in *our* code.) Given that increasing complexity is inevitable regardless of whether we choose PEP 572 or your suggestion, it is better to choose the option which keeps binding-expressions and assignment statements separate, since they are two different concepts. -- Steve _______________________________________________ Python-Dev mailing list [email protected] https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com