Missing imports in VS Code

[felixhammerl]

Hi folks,

I am not sure if this is an issue that this codebase should concern itself with, but here's something strange that I have noticed when using VS Code and Pylance.

When using the from hamcrest import * preamble in my tests, VS Code spits out the following error:

It seems that for whichever reason, Pylance fails to resolve won't resolve nested wildcard imports. When explicitly importing, the submodules, it works as expected.

from hamcrest import *
from hamcrest.core import assert_that

[felixhammerl]

Digging into it, I think that it's this behavior that causes Pylance to trip up: https://docs.python.org/3/tutorial/modules.html#importing-from-a-package

Now what happens when the user writes from sound.effects import *? Ideally, one would hope that this somehow goes out to the filesystem, finds which submodules are present in the package, and imports them all. This could take a long time and importing sub-modules might have unwanted side-effects that should only happen when the sub-module is explicitly imported.

The only solution is for the package author to provide an explicit index of the package. The import statement uses the following convention: if a package’s init.py code defines a list named all, it is taken to be the list of module names that should be imported when from package import * is encountered. It is up to the package author to keep this list up-to-date when a new version of the package is released. Package authors may also decide not to support it, if they don’t see a use for importing * from their package. For example, the file sound/effects/init.py could contain the following code:

If all is not defined, the statement from sound.effects import * does not import all submodules from the package sound.effects into the current namespace; it only ensures that the package sound.effects has been imported (possibly running any initialization code in init.py) and then imports whatever names are defined in the package.

It seems that the Python runtime can deal with this, as my tests pass, but we should use __all__ to make give an indication of what all should be loaded.