Understanding What Python Is

A programming language is a type of computer language that is used to implement algorithms, which are instructions for performing particular actions — in other words, to make the computer do what the programmer wants it to do.

Python is a general-purpose programming language rather than a domain-specific programming language. As you might guess, a general-purpose programming language is a programming language designed for general programming use rather than for use in a specific area of computing. By contrast, a domain-specific programming language is a programming language designed for use in a specific area of computing. For example, Wolfram Mathematica is a programming language designed for symbolic mathematics; it is not designed for, and is not suitable for, general programming use, so it is domain specific.

Understanding Cross-Platform Programming

Python enables you to write applications that work on many different computing platforms. A computing platform means the hardware and operating system that together constitute a functional computer.

This book covers three widely used computing platforms:

• PC hardware running Microsoft’s Windows operating system. This book uses Windows 10 and Windows 11 for examples.
• Apple Macintosh hardware running Apple’s macOS operating system. This book uses macOS version 12, also known as macOS Monterey, for examples.
• PC hardware running the Linux operating system. Linux comes in many different versions, called distributions. This book uses the popular Ubuntu distribution for Linux examples.

Python fully supports the Windows, Mac, and Linux platforms, but it also supports many other platforms. These platforms range from those for personal devices, such as Apple’s iOS operating system and iPhones, all the way up to “big-iron” platforms for minicomputers and mainframes, such as IBM’s AIX and HP’s HP-UX. Python versions for some platforms come from third-party vendors.

Understanding Who Uses Python

Many different types of programmers use Python. Here are two examples:

• Web developers use Python to create web services that provide custom information in response to requests they receive. For example, when you visit a web forum, Python may be generating some or all parts of the page that the server sends to your browser.
• Scientists, mathematicians, and engineers across many fields use Python to perform data analysis, because Python provides powerful and convenient tools for processing and applying complex equations to statistical data.

Know Where You Can Get Python

You can download Python for free from the Python Software Foundation’s website, www.python.org. However, you may not need to download Python, because it may already be installed on your computer.

Windows typically does not include Python; see the section “Install Python on Windows,” later in this chapter, for instructions on installing Python.

macOS includes Python 2. See the section “Install Python on the Mac,” later in this chapter, for instructions on seeing which version a Mac contains and updating Python if necessary.

Many Linux distributions include one or more versions of Python. As of this writing, more distributions include Python 2 than include Python 3, but some distributions include both versions; see the following section, “Choose the Right Version of Python.” See the section “Install Python on Linux If Necessary,” later in this chapter, for instructions on checking the version and updating if necessary.

To find versions of Python for iOS or iPadOS, open the App Store app on the iPhone or iPad and search for python. Pythonista is a popular app, but there are plenty of other choices. Similarly, to find versions of Python for Android, open the Play Store app on your Android device and search for python.

Understanding Python 2 and Python 3

Two major versions of Python are currently in wide use: Python 2, released in 2000, and Python 3, released in 2008.

Each version uses a sequence-based numbering scheme for intermediate releases. For example, “Python 2.7.1” means Python 2, the seventh minor version, and the first update to that minor version. Similarly, “Python 3.10.0” means Python 3, the tenth minor version, and the initial release of that minor version.

The Python Software Foundation officially discontinued, or “sunset,” Python 2 on January 1, 2020. Sunsetting means that the Python Software Foundation will not develop Python 2 any further, even if researchers discover serious security issues in it. Because Python 2 has been sunset, the Python Software Foundation recommends that all users upgrade to Python 3 as soon as possible. The final version of Python 2 was 2.7.18.

With most software, such as business productivity apps or multimedia apps, upgrading to a newer version is a straightforward and painless procedure: You upgrade to the new version, and everything still works, even if the user interface has changed and the new version of the app provides extra features.

Python 3 offers compelling new features that Python 2 does not have; even better, Python 3 typically runs faster than Python 2. However, Python 3 is not fully compatible with Python 2, and some Python 2 code may not run successfully in Python 3. This is why many companies and organizations still have not upgraded from Python 2 to Python 3. The more Python 2 code a company or organization has built up, the more time, effort, and expense it will take to upgrade to Python 3.

Which Version of Python Do You Need?

You almost certainly need Python 3 unless your workplace uses Python 2 and is not migrating to Python 3. For example, your employer may have developed substantial amounts of Python 2 code that is not fully compatible with Python 3 and may therefore be sticking with Python 2.

If you are planning to start developing code from scratch, you should definitely choose Python 3 rather than Python 2.

You can install both Python 2 and Python 3 alongside each other and use each version when you need it.

macOS and many Linux distributions include Python 2 because they require Python 2 to run some software packages included with the operating system or distribution. Because of this requirement, you should not uninstall Python 2, even if you do not need it. Instead, simply leave Python 2 alone, install Python 3, and use Python 3 for development.

Windows does not need Python 2, so normally, you should install Python 2 on Windows only if you need it.

What Are the Two Build Types of Python?

Python.org makes available two types of builds of Python, stable builds and development builds:

Stable build. A stable build is a build that has been fully tested and approved for distribution.

Development build. A development build is an experimental build used for testing and compatibility. Development testers provide feedback on changes and new features before they are finalized and added to stable builds.

You may also see Python builds described as “release candidates.” A release candidate is a near-final development build made available — usually to a wide audience — for final testing. A release candidate is stable in theory but not always so in practice.

Which Build Type Should You Get?

You will almost always want to get a stable build of Python rather than a development build. Normally, you will want to get the latest stable build of Python so that you have access to the latest features. However, if your company, organization, or school is using an older stable build of Python, it will likely want you to use that build for compatibility.

When Will Python 4 Be Released?

The Python Software Foundation has not announced a release date for Python 4. In fact, Guido van Rossum has cast doubt on whether there will ever be Python 4, given how difficult and protracted the move from Python 2 to Python 3 turned out to be. Instead, the Python Software Foundation is continuing to develop Python 3.

As of this writing, the current stable version of Python is 3.10.4. Future versions of Python 3 are likely to use numbering such as 3.11.x, 3.12.x, and so on.

What Is a Code Editor?

A code editor is an app that is designed and built to make the writing of programming code easier, faster, and more efficient. While you can write code using any text editor or word processor, these apps do not provide the programming-specific features that a code editor gives you.

A code editor typically includes features such as the following:

• Syntax evaluation and highlighting. As you program, the editor determines the code’s different elements and highlights them in different colors and font styles (A) to help you identify them visually.
• Automatic completion of code. When you start typing a keyword or another known element, the code editor displays suggestions for completing it. By accepting these suggestions, you can work faster.
• Multifile interface. Whereas most word processors keep each document in a separate window, many code editors use a tabbed interface (B) that enables you to open multiple files in the same window and switch quickly from one file to another by clicking the appropriate tab. Many text editors likewise use a tabbed interface.
• Line numbers. The code editor automatically displays line numbers (C) so that you can easily navigate through your code.

What Is an Integrated Development Environment?

An integrated development environment, or IDE, is an application designed for developing code. The development environment is integrated because you can both write the code in the environment and run the code to make sure it works correctly.

An IDE typically provides similar features to those in a code editor, such as syntax evaluation and highlighting, automatic code completion, and the ability to switch easily among multiple files. To these features the IDE adds tools for testing and debugging your code.

For example, the figure shows the PyCharm IDE. In the upper-left corner is the Project pane (D), which enables you to navigate among the files in your current project; gives you access to external libraries, repositories containing code you can add; and provides a scratch window for quick work and notes, and consoles for running code outside the IDE. In the upper-right corner is the Code pane (E), where you write your code. And across the bottom is the Run window (F), in which the output from your running code appears.

Which IDEs Can I Use for Creating Python Code?

You can use a bewildering variety of IDEs for creating Python code. Some IDEs are designed for use only with Python, whereas other IDEs are designed for use with various programming languages. Some IDEs are much fuller featured than others and provide more help as you work. Extra help may be welcome while you are starting to use Python but may become annoying as you gain more experience.

Here are three examples of IDEs for Python:

• IDLE. IDLE is a minimalist IDE that is included in the Python packages you can download from the Python Software Foundation website, www.python.org. IDLE, shown in the figure, uses multiple separate windows for the Editor (G), the Shell (H), and features such as Debug Control (I) rather than displaying multiple panes inside a single window.
• PyCharm. PyCharm (www.jetbrains.com/pycharm) is a full-featured IDE that comes in two editions. Normally, you would want the Community Edition, which is free and works only with Python. The other edition, Professional, is a paid version that has a free trial and works with HTML, JavaScript, and SQL, as well as Python.

  

• Thonny. Thonny (https://thonny.org) is a lightweight IDE designed to help beginners come to grips with Python coding. Thonny offers three modes for different levels of experience: Simple Mode for beginners, Regular Mode for those who need greater control, and Expert Mode for advanced users. The accompanying figure shows Regular Mode.

Which Code Editors Can I Use for Python?

You have a wide choice of code editors suitable for programming Python. Here are three examples of code editors well worth your consideration:

• Sublime Text. Sublime Text, shown in the “What Is a Code Editor?” subsection earlier in this section, is a powerful text editor with a minimalist interface that provides as much space as possible for displaying your code files. Sublime Text supports more than 40 other programming languages as well as Python. You can download an evaluation version of the app from the Sublime Text website, www.sublimetext.com; the app then costs $99 for a 3-year subscription.
• Atom. Atom, shown on this page, is a highly customizable code editor that makes working with multiple files easy. As of this writing, Atom seems to place greater demands on the computer running it than the other code editors listed here; as a result, Atom tends to run more slowly. Atom is free to download from the Atom website, https://atom.io.
• Visual Studio Code. Visual Studio Code is a powerful code editor developed by Microsoft. It is separate from Microsoft’s Visual Studio IDE and runs on Windows, macOS, and Linux. See the following section for more information.

Which Code Editor or IDE Does This Book Recommend for Python?

This book recommends that you use Visual Studio Code as your main coding tool for working with Python, at least while using this book. Visual Studio Code is free, provides powerful coding features, and is widely used for various programming languages from C +  +  and C# to PHP and PowerShell.

While Visual Studio Code is generally described as a code editor, it also provides full-scale debugging features, so it is effectively also an IDE.

The following section, “Download and Install Visual Studio Code,” shows you how to get the app on your Windows PC, Mac, or Linux box. Subsequent sections show you how to set Visual Studio Code’s look by applying a theme, install Python-related extensions to provide extra functionality, and configure some essential settings.