Setting up Python
=================

  Check that both pip and at least version 3.6 of Python are installed. 
  QuadlogSCADA and some of the Python modules make use of async/await syntax 
  that earlier versions of Python lack.

Select Python Interpreter
-------------------------

  List and check the current versions of Python installed:
  
  .. code:: console

    $ ls -w40 /usr/bin/python3.*
  
    /usr/bin/python3.7
    /usr/bin/python3.7-config
    /usr/bin/python3.7m
    /usr/bin/python3.7m-config
    /usr/bin/python3.8
    /usr/bin/python3.8-config

  Select the highest Python version for your system for system default. Set the 
  alternatives as follows and then check.

  .. code:: console

    $ update-alternatives --install /usr/bin/python python /usr/bin/python3.8 1
    $ python --version

Python Packages
---------------

  Install the following Python3 packages. 

  .. code:: console

    $ apt install python3-dev
    $ apt install python3-venv
    $ apt install python3-pip

  Then upgrade pip to ensure it is te latest version.

  .. code:: console

    $ pip3 install -U pip
  
  It might be that some additional Python modules need installing, such as `distutils`. 
  
  .. code:: console

    $ apt install python3-distutils
  
Package Management Tool
-----------------------

  Poetry is a dependency management tool for Python and it is used to assist in the 
  management of setting up quadlogSCADA source files. For information on Poetry, visit
  https://python-poetry.org/docs/
  
  Frst install 'curl' so that Poetry can be downloaded and then installed.

  .. code:: console

    $ apt install curl
    $ curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py | python

  Once Poetry has completed its installation, a message to set the path to Poetry, 
  by either re-login the user session or to set it by command as below. 
  
  .. code:: console

    $ source $HOME/.poetry/env


  Poetry checks

  .. code:: console

    $ poetry config --list
    cache-dir = "/home/dev/.cache/pypoetry"
    virtualenvs.create = true
    virtualenvs.in-project = true
    virtualenvs.path = "{cache-dir}/virtualenvs"  # /home/dev/.cache/pypoetry/virtualenvs
  
  
  set for local virtual environment  

  .. code:: console

    poetry config virtualenvs.path /home/dev/workspace_python/quadlog-scada --local