Logging does support passing a callable, if indirectly. It only calls __str__
on the object passed if debugging is enabled.
class Defer:
def __init__(self,fn):
self.fn = fn
def __str__(self):
return self.fn()
def some_expensive_function():
return "hello"
logging.basicConfig()
logging.debug(Defer(some_expensive_function))
From: Python-list <python-list-bounces+gweatherby=uchc....@python.org> on
behalf of Barry <ba...@barrys-emacs.org>
Date: Friday, October 7, 2022 at 1:30 PM
To: MRAB <pyt...@mrabarnett.plus.com>
Cc: python-list@python.org <python-list@python.org>
Subject: Re: Ref-strings in logging messages (was: Performance issue with
CPython 3.10 + Cython)
*** Attention: This is an external email. Use caution responding, opening
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> 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.
Barry
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