That PR seems to make \' and \" not special in general right?

I think this is a more limited proposal, to only change the behavior when \ is at the end of a string, so the only behavior difference would never receiving the error "SyntaxError: EOL while scanning string literal"

How would you know where the end of a string is? I think this is one of those things that's easy to look at for a human and figure out the intent, but not so easy for the lexer, without some heuristics and backtracking. If the trailing single quote is removed below, it changes from "backslash in the middle of a string" to "backslash at the end of a string, followed by an arbitrary expression.

r'\' + "foo"'

Eric

In which case there should be no backwards compatibility issue.

Damian

On Sat, May 28, 2022 at 12:20 PM Serhiy Storchaka <storchaka@gmail.com> wrote:

28.05.22 12:22, Steven D'Aprano пише:
> Now that we have a new parser for CPython, can we fix the old gotcha
> that raw strings cannot end in a backslash?
>
> Its an FAQ and has come up again on the bug tracker.
>
> https://docs.python.org/3/faq/design.html#id26
>
> https://github.com/python/cpython/issues/93314

I do not think that we can allow this, and it is not related to parser.

Few years ago I experimented with such change:
https://github.com/python/cpython/pull/15217

You can see that it breaks even some stdlib code, and it will definitely
break many third-party packages and examples. Technically we can do
this, but the benefit is small in comparison with the cost.

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