Python Programming¶

Introduction¶

Before you attempt to install the Python programming language on your computer, it is worth taking time to build a mental model about what a Python program actually is and what happens when it runs on your computer. Sounds abstract, right? In a way, it is! But, building and regularly updating a mental model for Python programs will eliminate some of the confusion that arises when your program does something initially unexpected.

Notional Machine¶

The book called Teaching Tech Together summarizes, in twelve statements, a notional machine for the syntax, semantics, and behavior of a Python program. Please read the twelve components of the notional machine for Python and identify both the parts of it that you understand the best and those that are confusing. You can share your ideas with the proactive community and then clarify points that are confusing for others and receive feedback on your own points of confusion. Although you should develop an intuitive understanding of all twelve parts of the notional machine, let's review some of them now!

• Every piece of data is stored in a two-part structure. The first part says what type the data is and the second part is the actual value: This means that we can think of the variables in a Python program as a "box" that has two regions in it. The first region stores the type of data (e.g., it is a str that stores character-based data consisting of letters and symbols) and the second region stores the actual data itself (e.g., the word "proactive" could be stored inside of an variable of type str).

• Booleans, numbers, and character strings are never modified after they are created: This means that variables of type bool, int, and str are immutable and thus they never change once they are created and stored in the memory of a Python program. Knowing that these variables do not change after creation will help you to avoid some fundamental misunderstandings that often lead to defects in your program and thwart your goal to becoming a proactive programmer.

• When code is executed, Python steps through the instructions, doing what each one tells it to in turn: This reveals that the Python programming language has an interpreter, called python, that you can use to run a Python program.¹ Intuitively, the process of running a Python program involves the interpreter running each instruction and then following its control flow that shows which instruction to run next.

Installing Python¶

Now that you have an intuitive understanding of how a program written in the Python programming language works, you are ready to install it on your own computer! In his book Introduction to Computation and Programming Using Python John Guttag writes "By now, all of the important public domain Python libraries have been ported to Python 3. Today, there is no reason to use Python 2." Given this observation, this site encourages you to install the most up-to-date Python 3 version on your computer and ensure that it is invoked by the running command python in your terminal window. To get started with the installation of Python, you should review tutorials like these:

• Setting Up Python on Windows
• Python 3 Installation and Setup Guide
• How to Install Python 3 and Set Up a Local Programming Environment on Windows 10

If you are learning to become a proactive programmer while using a computer running either a Linux or a MacOS, then you should install Python 3.10 by using either the tool called Pyenv or the tool called asdf. If you are instead using a computer that runs Windows 10, then you can attempt to install Python 3.10 using either Pyenv-win or the installation instructions in one of the aforementioned articles. Please remember that, if you are installing Python on Windows it should either be a complete version of the most recent version of Python (i.e., Python 3.10) and it should be executable through the use of the python command in your terminal. You can confirm that you have the correct version of Python installed on your computer by typing python --version in your terminal window and then looking for the expected version number. It is important that you do not install and attempt to use any older versions of this programming language than Python 3.8.

Now that you have Python 3.10 installed on your computer you should complete all of the steps in the tutorial called Getting Started with Python in VS Code. When you complete this tutorial make sure that select your installed version of Python through VS Code and write, run, and debug a "Hello World!" program written in Python. Along with confirming that you can run the "Hello World!" Python program through VS Code, you should ensure that you can run the same program in your terminal window by using the python program.

Depending on your computer's hardware, operating system, and supporting software, you will find numerous tutorials that will explain how to install all of the software development tools needed for proactive programming. For instance, Ian Wootten's article called Setting Up a New M1 mac for Development explains, among many other steps, how to install Python on a laptop running MacOS. Regardless of which approach you adopt for installing Python on your computer, make sure that you take careful notes at each step and plan for having to repeat specific steps until you can confirm that you can implement and run a basic program on your computer. If you get stuck or if you have advice to share, make sure that you connect with the other members of the proactive community!

Now you are ready to install a tool that supports Python packaging!