documentation request: how to follow imports within a virtualenv

[SKalt]

Issue Scope

1. provide an example in the guided tour on following imports in a virtualenv
2. clarify CLI argument documentation to show how to pass multiple directories to --search-path

The Story

I wanted to write an example of checking pip-installed imports using pyre. After reading through the documentation, I found that vanilla source activate my-venv; pyre --source-directory to/check check was not detecting packages I had pip installed in my virtualenv. Reading #64, I tried passing in a unix-style path, separated by :s. This failed with a semi-informative error message, pyre_check.exceptions.EnvironmentException: colon/separated:list/of:paths/to/search is not a valid directory. I found passing in multiple --search-paths worked:

get_path_to_check() { 
  python <<eof
import sys
from os.path import isdir
result = ' '.join(
    f'--search-path {i}' for i in sys.path
    if isdir(i) and 'site-packages' in i
)
print(result)
eof
}
pyre $(get_search_path) --source-directory to/validate check

This solution isn't 100% intuitive. The guided tour should include an example like this of working in a virtualenv to make pyre easier to adopt. Updating the --search-path SEARCH_PATH documentation from

Additional directories with modules and stubs to include in type environment

to something like

Adds an additional directory with modules and stubs to include in type
environment each time it is passed

would also clarify pyre usage.

[dark]

Thanks for the report, would you like to provide pull requests to clarify the usage of --search-path and how that can be used in a virtualenv?

[SKalt]

Sure thing! Full disclosure: I'm only familiar with pipenv and conda envs. I'll see if I can set up minimal gists for pipenv and virtualenv; I've got one for conda.

Aside: looking through the code, I noticed at ./client/configuration.py#Configuration.__init__ it looks like you could ingest the sys.path that pyre is running in. Do you think that would make working with python envs simpler or introduce gotchas?

[dark]

Sorry for the late reply, but this dropped from my radar somehow. I am looking at the PR, I have minor comments on that one.

As for the second point you mentioned, we might as well extend the pre-existing flag (--preserve-pythonpath) to cover sys.path as well. I'd rather not add another config flag to prevent creating a configuration hell. If you could write a PR for it, it would be great, thanks!

[omry]

I am having issues running inside a conda environment as well.
pyre does not find installed packages.

tests/examples/test_dataclass_example.py:3:0 Undefined import [21]: Could not find a module corresponding to import `pytest`.

Are virtual environments supported?