.. _installation:

Installation
============

There are two ways of installing the FVM:

Installing from pip
-------------------

The recommended way of installing the FVM is to install it from the Python
Package Index (`PyPI <https://pypi.org/>`_), using pip:

.. code-block:: zsh

   pip3 install fvm-formal

.. note::

   In recent pip versions you may need to create a python virtual environment
   (``venv``), or else you will get an "externally-managed-environment" error
   when trying to install packages using pip.

   The following code:

   .. code-block:: zsh

      python3 -m venv venv       # Create the venv in the venv folder
      source venv/bin/activate   # Activate the newly created venv

   will create a ``venv`` and activate it in the current shell. With the
   ``venv`` activated, ``pip3 install`` will install the FVM inside the venv.

   See https://docs.python.org/3/tutorial/venv.html for details.


Installing from the git repository
----------------------------------

Installing from the repository allows to perform an editable installation
(passing the ``-e`` flag to ``pip3 install``), so you can modify the python sources
and the changes will be immediately available.

This option is also interesting if you want a specific version that was not
tagged and pushed on PyPI, for example if you need to check out a specific
commit, branch or tag.

.. code-block:: zsh

   git clone https://gitlab.com/fvmformal/fvm.git
   pip3 install -e fvm

.. note::

   The FVM is also available on github:

   .. code-block:: zsh

      git clone https://github.com/fvmformal/fvm.git
      pip3 install -e fvm

.. note::

   The ``-e`` option tells python that the FVM sources reside in the recently
   cloned ``fvm`` directory. If you intend to remove that directory, you should
   remove the ``-e`` flag, but of course in that case the installation will not
   be editable.