commit | d0ff929b53a7db85860519b937ba16f3e21dd628 | [log] [tgz] |
---|---|---|
author | Shuhei Takahashi <nya@chromium.org> | Thu Jul 20 13:35:37 2017 +0900 |
committer | chrome-bot <chrome-bot@chromium.org> | Fri Jul 21 06:32:04 2017 -0700 |
tree | 1d3408c716d7764280b65c092ea1164ef6679920 | |
parent | 5cda24fbb171f62bf59f3065de5119c40b185df0 [diff] |
Update comment in python_venv. Comment is updated so that one can tell where this script was copied from. BUG=chromium:733103 TEST=None Change-Id: I733e55dbc9aefdc60f074eed86c5544218487649 Reviewed-on: https://chromium-review.googlesource.com/578702 Commit-Ready: Shuhei Takahashi <nya@chromium.org> Tested-by: Shuhei Takahashi <nya@chromium.org> Reviewed-by: Allen Li <ayatane@chromium.org>
This repository provides a common Python virtualenv interface that infra code (such as chromite) can depend on.
Virtualenv users should mimic this repository, which itself uses virtualenv for running unit tests.
venv
directory. All packages and modules in this directory will be importable inside the virtualenv.requirements.txt
file inside venv
to list external packages to install.bin/python_venv
and bin/turtle
which serve as templates.To add packages to this repository, run:
$ pip wheel -w path/to/pip_packages -r path/to/requirements.txt
Commit the changes and make a CL.
The bin/create_venv
script prepares a virtualenv using a requirements.txt
file.
$ bin/create_venv requirements.txt
The script will print the path to the virtualenv to stdout. Note that the output ends with a newline; Bash handles this, but Python does not.
To run the virtualenv Python, call bin/python
under the virtualenv directory.
Together, this might look up:
$ venv=$(bin/create_venv requirements.txt) $ ${venv}/bin/python
NOTE: it is not generally safe to run the other scripts in the virtualenv's bin
directory due to hard-coded paths. Instead of running bin/pip
for example, use bin/python -m pip
.
NOTE: Do not use this for third party dependencies (stuff not owned by ChromiumOS)! This should only be used to set up imports for stuff we own. For example, importing python-MySQL SHOULD NOT use this, but importing chromite from Autotest MAY use this.
This should be handled by the minimum amount of code in the package's __init__.py
file.
Example:
"""Autotest package.""" import sys # Use the minimum amount of logic to find the path to add _chromite_parent = 'site-packages' sys.path.append(_chromite_parent)
A solid understanding of the Python import system is recommended (the link is for Python 3, but it is informative).
In brief, __init__.py
is executed whenever a package is imported. A package is imported before any submodule or subpackage is imported. A package is only imported once per Python process; future imports are looked up in sys.modules
. Thus, __init__.py
will modify sys.path
exactly once and is guaranteed to be run before anything in that package is imported.