[Python-Dev] Make re.compile faster (original) (raw)

Barry Warsaw barry at python.org
Tue Oct 3 10:14:58 EDT 2017

On Oct 3, 2017, at 01:35, Serhiy Storchaka <storchaka at gmail.com> wrote:

diff --git a/Lib/string.py b/Lib/string.py index b46e60c38f..fedd92246d 100644 --- a/Lib/string.py +++ b/Lib/string.py @@ -81,7 +81,7 @@ class Template(metaclass=TemplateMetaclass): delimiter = '$' idpattern = r'[a-z][a-z0-9]*' braceidpattern = None - flags = re.IGNORECASE + flags = re.IGNORECASE | re.ASCII def init(self, template): self.template = template patched: import time: 1191 | 8479 | string Of course, this patch is not backward compatible. [a-z] doesn't match with 'ı' or 'ſ' anymore. But who cares? This looks like a bug fix. I'm wondering if it is worth to backport it to 3.6. But the change itself can break a user code that changes idpattern without touching flags. There is other way, but it should be discussed on the bug tracker.

It’s definitely an API change, as I mention in the bug tracker. It’s probably safe in practice given that the documentation does say that identifiers are ASCII by default, but it also means that a client who wants to use Unicode previously didn’t have to touch flags, and after this change would now have to do so. flags is part of the public API.

Maybe for subclasses you could say that if delimiter, idpattern, or braceidpattern are anything but the defaults, fall back to just re.IGNORECASE.

Cheers, -Barry

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