[Python-ideas] Show deprecation warnings in the interactive interpreter (original) (raw)

Steven D'Aprano steve at pearwood.info
Wed Feb 25 10:55:59 CET 2015

On Wed, Feb 25, 2015 at 07:39:50PM +1100, Ben Finney wrote:

Serhiy Storchaka <storchaka at gmail.com> writes:

> What you are think about turning deprecation warnings on by default in > the interactive interpreter? In its favour: Exposing problems early, when they can easily be fixed, is good. To its detriment: Making the interactive interpreter behave differently by default from the non-interactive interpreter should be resisted; code which behaves a certain way by default in one should behave the same way in the other, without extremely compelling justification.

The ship has sailed on that one. In the interactive interpreter:

py> 23 # Evaluating bare objects prints them. 23 py> _ 23 py>

But non-interactively:

[steve at ando ~]$ python -c "23

" Traceback (most recent call last): File "", line 2, in NameError: name '_' is not defined

I think there are three questions that should be asked:

(1) How does one easy and simply enable warnings in the interactive interpeter?

(2) If they are enabled by default, how does one easily and simply disable the again? E.g. from the command line itself, or from your PYTHONSTARTUP file.

(3) Should they be enabled?

I can't give an opinion on (3) until I know the answer to (1) and (2). I tried looking at the warnings module and the sys module but nothing stands out to me.

-- Steve

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