[Python-ideas] Better error messages [was: (no subject)]

[Nick Coghlan]

On 30 November 2016 at 19:05, Paul Moore <p.f.moore at gmail.com> wrote:
> On 30 November 2016 at 02:14, Stephen J. Turnbull
> <turnbull.stephen.fw at u.tsukuba.ac.jp> wrote:
>> Wouldn't
>>
>>     NameError: Python doesn't recognize the name "log".  Perhaps
>>     you need to import the "math" module?
>
> ... and of course up until this example, I'd assumed you were talking
> about the log function from the logging module :-)
>
> I'm a strong +1 on better error messages, but there's always a risk
> with heuristics that the resulting messages end up worse, not better.
>
> Maybe keep it simpler:
>
>     NameError: Python doesn't recognize the name "log". Maybe you
> misspelled the name, or did you mean to import the function from a
> module?
>
> and don't try to guess the user's intent.

This brings up a point that I was going to mention earlier: when it
comes to specialised learning environments, the folks developing the
curriculum also know *what problem the student is working on*, and can
tailor their error messages accordingly.

The reference interpreter is never going to be able to guess intent
like that due to the sheer scope of Python's use cases - by covering
everything from students writing "Guess a number" games to mechanical
engineers modeling and tuning race car performance to sysadmins
automating service deployments to web developers responding to user
requests to data analysts trying to make sense of noisy data, we end
up being *really* limited in the assumptions we can make about what a
user was really trying to do when they accidentally ask for something
nonsensical.

Tweaking some of the default representations to mention common
problems should be OK, though. While some veteran programmers may find
such prompts a bit condescending, they'd be better equipped than
beginners to opt in to alternative exception display options that omit
the hints.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia