26.04.18 22:02, Lukasz Langa пише:
On Apr 26, 2018, at 11:37 AM, Serhiy Storchaka <storchaka@gmail.com> wrote:
I propose to change the Python syntax by adding a requirement that there should be a whitespace or delimiter between a numeric literal and the following keyword. -1
This would make Python 3.8 reject code due to stylistic preference. Code that it actually can unambiguously parse today.
Of course I don't propose to make it a syntax error in 3.8. It should first emit a SyntaxWarning and be converted into an error only in 3.10. Or maybe first add a rule for this in PEP 8 and make it a syntax error in distant future, after all style checkers include it.
I agree that a formatting style that omits whitespace between numerals and other tokens is terrible. However, if you start downright rejecting it, you will likely punish the wrong people. Users of third-party libraries will be met with random parsing errors in files they have no control over. This is not helpful.
And given BPO-33338 the standard library tokenizer would have to keep parsing those things as is.
Making 0or[] working again is also not worth it since that's been broken since Python 2.6 and hopefully nobody is running Python 2.5-only code anymore.
What we should instead is to make the standard library tokenizer reflect the behavior of Python 2.6+.
The behavior of the standard library tokenizer doesn't contradict rules. It is the most natural behavior of regex-based tokenizer. Actually the behavior of the building tokenizer can be incorrect. In any case accepting `1if 2else 3` and rejecting `0or[]` looks weird. They should use the same rule. "0or" and "2else" should be considered ambiguous or unambiguous in the same way.