Notes and guides on programming topics¶
Virtual Environments with virtualenv¶
virtualenv¶
virtualenv is a third party Python package for handling isolated virtual environments. It is more feature-rich than the standard library package venv.
virtualenvwrapper-win¶
virtualenvwrapper-win,
is an extension package to virtualenv, which provides easy-to-use wrappers
around the commands.
Most of the commands shown below are for virtualenvwrapper-win
Note
This package works only in the regular Windows Command Prompt, not in PowerShell.
The -win suffix, which is necessary for the Windows version of the package.
First time setup¶
Install the two packages if they aren’t already:
pip install virtualenv
pip install virtualenvwrapper-win
Creating a virtual environment¶
mkvirtualenv <new_env_name>
The new virtual environment is then created and automatically activated.
The active environment is shown in parenthesis in the left side of the prompt.
Pair environment with working directory¶
Pair an environment with the current working directory by
setprojectdir .
This pairs the active environment to the current working directory.
Deactivating an environment¶
To deactivate an environment that is currently active, simply close the prompt that has the environment open. The parenthesis on the left showing the active environment will have disappeared once a new prompt is opened.
Alternatively, if you want to continue working in the same prompt, deactivate directly by
deactivate
Obviously, virtualenvwrapper-win knows exactly what environment is active, and thus which one to deactivate.
Start working on an existing environment¶
To start working on a project that is tied to an existing environment
workon <env_name>
The current directory will be changed to the root directory of the project that is paired with the virtual environment.
Remove an environment¶
rmvirtualenv <env_name>
Useful commands¶
List all virtual environments
lsvirtualenv
See the packages installed in the active virtual environment
pip list
Note on using virtualenv in PowerShell¶
As mentioned above, PowerShell is not supported to virtualenvwrapper-win.
Although, virtualenv does support PowerShell. However, it has a more verbose syntax since it misses a wrapper package like virtualenvwrapper for Bash and virtualenvwrapper-win for Windows Command Prompt.
E.g. an environment can be activated by running the activate.ps1 PowerShell script tied to it.