Contents

• Back up your computer
• Install Python v.3
• Create a Directory
• Install Komodo Edit
• Start Komodo Edit
  • Configure Komodo Edit
• Step 2 – ‘Hello World’ in Python
• Interacting with a Python shell

Back up your computer

It is always important to make sure you have regular and recent backups of your computer. This is just good advice for life, and is not limited to times when you are engaged in programming.

Install Python v.3

Go to the Python website, download the latest stable release of the Python programming language (Version 3.8 as of November 2019) and install it by following the instructions on the Python website.

Create a Directory

To stay organized, it’s best to have a dedicated directory (folder) on your computer where you will keep your Python programs (e.g., programming-historian) and save it anywhere you like on your hard drive.

Install Komodo Edit

Komodo Edit is a free and open source code editor, but you have many other text editing options if you want to use another programme. You can download a copy from the Komodo Edit website.

Start Komodo Edit

It should look something like this:

If you don’t see the Toolbox pane on the right hand side, choose View -> Tabs -> Toolbox. It doesn’t matter if the Project pane is open or not. Take some time to familiarize yourself with the layout of the Komodo editor. The Help file is quite good.

Configure Komodo Edit

Now you need to set up the editor so that you can run Python programs.

Choose Edit -> Preferences -> Languages -> Python 3 and then select Browse. Now select C:\Users\YourUserName\AppData\Local\Programs\Python\Python38-32) If it looks like this, click OK:

Next, in the Preferences section select Internationalization. Select Python from the drop-down menu titled Language-specific Default Encoding and make sure that UTF-8 is selected as the default encoding method.

Next choose Toolbox->Add->New Command. This will open a new dialog window. Rename your command to ‘Run Python’. Under ‘Command’, type:

%(python3) %f

If you forget this command, Python will hang mysteriously because it isn’t receiving a program as input.

Under ‘Start in’, enter:

%D

If it looks like this, click OK:

Your new command should appear in the Toolbox pane. You may need to restart your machine after completing this step before Python will work with Komodo Edit.

Step 2 – ‘Hello World’ in Python

It is traditional to begin programming in a new language by trying to create a program that says ‘hello world’ and terminates. We will show you how to do this in Python and HTML.

Python is a good programming language for beginners because it is very high-level. It is possible, in other words, to write short programs that accomplish a lot. The shorter the program, the more likely it is for the whole thing to fit on one screen, and the easier it is to keep track of all of it in your mind.

Python is an ‘interpreted’ programming language. This means that there is a special computer program (known as an interpreter) that knows how to follow instructions written in that language. One way to use the interpreter is to store all of your instructions in a file, and then run the interpreter on the file. A file that contains programming language instructions is known as a program. The interpreter will execute each of the instructions that you gave it in your program and then stop. Let’s try this.

In your text editor, create a new file, enter the following two-line program and save it to your programming-historian directory as hello-world.py

# hello-world.py
print('hello world')

Your chosen text editor should have a “Run” button that will allow you to execute your program. If all went well, it should look something like this (Example as seen in Komodo Edit. Click on the image to see a full-size copy):

Interacting with a Python shell

Another way to interact with an interpreter is to use what is known as a shell. You can type in a statement and press the Enter key, and the shell will respond to your command. Using a shell is a great way to test statements to make sure that they do what you think they should.

You can run a Python Shell by double-clicking on the python.exe file. If you installed version 3.8 (the most recent as of November 2019), then this file is probably located in the C:\Users\YourUserName\AppData\Local\Programs\Python\Python38-32 directory. In the shell window that opens on your screen type:

print('hello world')

and press Enter. The computer will respond with

hello world

When we want to represent an interaction with the shell, we will use -> to indicate the shell’s response to your command, as shown below:

print('hello world')
-> hello world

On your screen, it will look more like this:

Now that you and your computer are up and running, we can move onto some more interesting tasks. If you are working through the Python lessons in order, we suggest you next try ‘Understanding Web Pages and HTML‘