On Fri, 7 Oct 2022 18:28:06 +0100 Barry <ba...@barrys-emacs.org> wrote:
> > On 7 Oct 2022, at 18:16, MRAB <pyt...@mrabarnett.plus.com> wrote: > > > > On 2022-10-07 16:45, Skip Montanaro wrote: > >>> On Fri, Oct 7, 2022 at 9:42 AM Andreas Ames > >>> <andreas.0815.qwe...@gmail.com> > >>> wrote: > >>> 1. The culprit was me. As lazy as I am, I have used f-strings all over the > >>> place in calls to `logging.logger.debug()` and friends, evaluating all > >>> arguments regardless of whether the logger was enabled or not. > >>> > >> I thought there was some discussion about whether and how to efficiently > >> admit f-strings to the logging package. I'm guessing that's not gone > >> anywhere (yet). > > Letting you pass in a callable to call might help because that you could > > use lambda. > > Yep, that’s the obvious way to avoid expensive log data generation. > Would need logging module to support that use case. I have some logging code that uses eval() to evaluate expressions using locals and globals in a parent stack frame, together with a parser to find `{...}` items in a string. I guess this constitutes a (basic) runtime implementation of f-strings. As such it can avoid expensive evaluation/parsing when disabled, though it's probably slow when enabled compared to native f-strings. It seems to work quite well in practise, and also allows one to add some extra formatting features. For details see: https://git.ghostscript.com/?p=mupdf.git;a=blob;f=scripts/jlib.py;h=e85e9f2c4;hb=HEAD#l41 - Jules -- http://op59.net -- https://mail.python.org/mailman/listinfo/python-list