How to run virtual environments with different versions of Python

Always use a Virtual Environment

🦉 It is a wise move to always run your Python projects in a virtual environment.
🎈 Installing the many dependencies that the average Python program requires into your base OS can soon lead to a bloated system.
🍱 Better to run a virtual environment per project and keep everything clean and compartmentalized.

Python 2 and Python 3?

• With that in mind, I had a requirement recently to run a program that required Python 2.7. I was running Python 3.8 on my machine.
• I realized that a virtual environment itself wasn't going to be enough. By default my virtual environments were all using Python 3.8.

Here's how I approached the problem on Windows 10:

1. Install Python2.7 from python.org

   Make sure you take a note of where the .exe file is installed. On my Windows machine the path was:
   

   C:\Python27\python.exe
   

2. Install the Python package 'virtualenv' using pip:
   

   pip install virtualenv
   

3. Create a new virtual environment using the Python 2.7 executable.

   Here the virtual environment is called venv1 and it uses Python2.7.
   

   virtualenv -p C:\Python27\python.exe venv1
   

4. Activate the virtual environment.
   

   .\venv1\Scripts\activate
   

5. Now if I enter 'python' I can see that I'm using Python 2.7.18 rather than the default 3.8:
   

   (venv1) PS C:\Users\joe> python
   Python 2.7.18<snip>
   

6. To create a virtual environment with Python 3.8, I can just run virtualenv without the p flag:
   

   virtualenv venv2
   

✨👹✨
@joeneville_