venv

A python package that redirects imports to specified directories.

This allows for the creation of entirely virtual python environments without having to actually copy or link any files/directories.

Instead, you simply set the target directory in which certain packages or subsets of packages are contained.

Use-Case

When working on a project that consists of multiple git repositories, it is cumbersome to change files across repositories, and have run your python project without having to syncrhonize the files continuously.

To make this worse, the files needed for python to work are nested in the repository which makes often makes it impossible to use them directly with python without mounting directories and other nasty stuff.

Using venv you you no longer have to worry about the location of your python files, they can be in any directory. The most direct parent doesn't even have to be named like the package you want to access them through.

Instead, you let venv redirect all of your imports. This is done on a per directory basis. You can define a package (dotted notation allowed) and map it to a certain directory.

venv.map('sqlalchemy', 'libs/sqlalchemy/lib/sqlalchemy/')

This allows you to keep the entire sqlalchemy repositoriy in a subdirectory named libs/sqlalchemy and still be able to simply import sqlalchemy without having to adjust the python path.

Furthermore, you could now easily keep multiple versions of a library and change the version being used on a local scale, that does not affect your entire python installation.

venv is greedy

You can also redirect submodules instead of only redirecting entire packages. If you do both at the same time, you might wonder which one takes precendence.

venv will take the best match, that is the longest. So venv will import what intuitively makes sense.

You could also say venvis greedy.