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

On Tue, Nov 29, 2016 at 9:19 AM, Nathaniel Smith <njs@pobox.com> wrote:

This also suggests that the overall error-handling flow for 'import foo' should look like:

1) run foo.missing.py 2) if it raises an exception: propagate that 3) otherwise, if sys.modules["foo"] is missing: raise some variety of ImportError. 4) otherwise, use sys.modules["foo"] as the object that should be bound to 'foo' in the original invoker's namespace

+1, because this also provides a coherent way to reword the try/except import idiom: # Current idiom # somefile.py try: import foo except ImportError: import subst_foo as foo # New idiom: # foo.missing.py import subst_foo as foo import sys; sys.modules["foo"] = foo #somefile.py import foo ChrisA