[Python-Dev] Make stacklevel=2 by default in warnings.warn() (original) (raw)

Gustavo Carneiro gjcarneiro at gmail.com
Sun Sep 20 12:27:00 CEST 2015

On 20 September 2015 at 07:55, Nathaniel Smith <njs at pobox.com> wrote:

On Sat, Sep 19, 2015 at 11:44 PM, Serhiy Storchaka <storchaka at gmail.com> wrote: > For now the default value of the stacklevel parameter in warnings.warn() is > 1. But in most cases stacklevel=2 is required, sometimes >2, and I don't > know cases that need stacklevel=1. I propose to make the default value of > stacklevel to be 2. I think that unlikely this will break existing code. But > rather can fix existing bugs. If stacklevel=1 is required (I don't know > cases), it can be explicitly specified.

+1 I don't have enough fingers to count how many times I've had to explain how stacklevel= works to maintainers of widely-used packages -- they had no idea that this was even a thing they were getting wrong. OTOH I guess if there is anyone out there who's intentionally using stacklevel=1 they might be reasonably surprised at this change. I guess for some kinds of warnings stacklevel=2 is not obviously correct -- the one that comes to mind is "warning: the computer on the other end of this network connection did something weird, continuing anyway". OTOOH in this case I'm not sure stacklevel=1 is any better either, since the thing being warned about has nothing to do with the current call stack at all.

In this case you should use the logging module instead.

-- Gustavo J. A. M. Carneiro Gambit Research "The universe is always one step beyond logic." -- Frank Herbert -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20150920/54d9f022/attachment.html>

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