Technologist

When developing in Python I enjoy using Sublime Text, especially its ability to run/build right from Sublime by simply pressing COMMAND+B. Meaning that I dont have to go out of the editor to the terminal to run the Python program.

Sample Python Program:

In sublime, I can program, run the program and see the result, increasing my productivity:

But what if I want to run a Python Virtual Environment and its benefits (see developing-in-python-using-python-virtual-environments).
Once the virtual environment is activated your terminal will use the Python Virtual Environment just fine, but Sublime Text will not, it will continue to use the system-wide Python environment by default.

Example: Having a Python module (e.g. IPy) installed in your virtual environment, but not system-wide, and having the Python virtual environment active:

# Python code:

# Running from terminal – (OK):

# Running from Sublime – (NOT OK):

To make Sublime Text use the virtual environment you need to create a Sublime project and edit its properties to use the Virtual Env.

# Create Sublime Project
Go to Project -> Save Project As…
// I named mine blog.sublime-project

# Edit project properties by editing the file in sublime to be as follows:
Note:
Remember the name: label as this is how you will use the build with… option
The shell_cmd: label is the command that will run when you build. It is far from perfect as you have to hardcode the Python program in the configuration, but at least works.

# Prepare Sublime to use your new build system:
Tools -> Build Systems -> PYTHON_VENV

# Now you can now continue to code and use COMMAND+B to build/run your programs without leaving your Sublime Text editor:

When developing in Python you most likely will need to install Python modules that will provide some type of functionality, the process is very simple:

Install the Python package manager:

Install modules, for example ‘yaml’, this is without virtual environments, this is basically installing a Python module system-wide:

The above will install Python modules for the system, but to do so you need ‘root’ privileges (e.g. sudo), and there is a possibility that developers don’t have ‘root’ privileges.
Another important scenario to consider is that installing/updating/modifying system-wide Python modules could affect other existing Python projects in the same system.

A way to overcome the system-wide python dependencies is to work with your own virtual environment, which allows you to install Python modules in a Python virtual environment and without the need for ‘root’ privileges.

What this accomplishes is to have your Python projects have their specific dependencies met without affecting anyone else.

To develop using Python virtual environments, the system should have the virtualenv Python package first:

Now as a regular user (no root or sudo needed):
# Create (or cd into) your Python project folder

# Create Python Virtual Environment, you can name it what you want, I chose to name it ‘env’

# Activating the virtual environment
To use the virtual environment (as opposed to the system-wide Python environment) you need to activate it first. After it is activated you will see it in the left your command prompt.

# System-wide Python

# Activate Virtual Env

# Ready to use Python Virtual Env

# Installing modules in the virtual environment

# Uninstalling modules in the virtual environment

# Install multiple python modules from a requirements file
If your project has multiple Python modules required, it is better to create a requirements.txt file with the list of Python modules.

Then you can install all the listed Python modules in your virtual environment as follows:

# Deactivate virtual environment (go back to using system-wide Python)