[Python-ideas] PEP: Distributing a Subset of the Standard Library

[Stephen J. Turnbull]

Nick Coghlan writes:

 > While upstream changes turned out not to be necessary for the
 > "distributor breaking up the standard library" use case, they may
 > still prove worthwhile in making import errors more informative in the
 > case of "I just built my own Python from upstream sources and didn't
 > notice (or didn't read) the build message indicating that some modules
 > weren't built".

This case-by-case line of argument gives me a really bad feeling.  Do
we have to play whack-a-mole with every obscure message that pops up
that somebody might not be reading?  OK, this is a pretty common and
confusing case, but surely there's something more systematic (and
flexible vs. turning every error message into a complete usage manual
... which tl;dr) we can do.

One way to play would be an interactive checklist-based diagnostic
module (ie, a "rule-based expert system") that could be plugged into
IDEs or even into sys.excepthook.  Given Python's excellent
introspective facilities, with a little care the rule interpreter
could be designed with access to namespaces to provide additional
detail or tweak rule priority.  We could even build in a learning
engine to give priority to users' habitual bugs (including typical
mistaken diagnoses).

That said, I don't have time to work on it :-(, so feel free to ignore
me.  And I grant that since AFAIK we have zero existing code for the
engine and rule database, it might be a good idea to do something for
some particular obscure errors in the 3.7 timeframe.