The Weekly Squeak

Tag: learning

  • Lesson 5: Programming the Shooter Game in Squeak/Smalltalk

    Lesson 5: Programming the Shooter Game in Squeak/Smalltalk

    Lesson 5 – Designing Objects

    In this lesson, you will begin the process of creating your space shooter game by identifying and designing the key objects that will make up the gameplay. Having become familiar with the Squeak programming environment and basic concepts in previous lessons, it is now time to focus on the major components of the game. Understanding and determining these objects and their roles will lay the foundation for the game mechanics we will develop in upcoming lessons.

    You will be building a simple, classic space shooter game. The game will feature a user-controlled ship that can shoot, enemy creatures that can be destroyed, and a score that accumulates points for each enemy destroyed. These are some of the primary objects you will work with, but as you proceed, you may discover additional objects or find that you need to adjust the roles and responsibilities of those you have already defined.

    Object Roles and Responsibilities

    When designing your objects, it helps to focus on two key aspects: what the object is and what it does – that is, its roles and responsibilities. For example, the spaceship object is something you control, and its responsibility is to move and shoot at enemies. Similarly, the enemy object is something that can be destroyed when hit by a shot. Other objects, like the score object, also play important roles in your game.

    At this stage, you do not need to know all the objects you will need right away – this is perfectly fine! Object-oriented programming (OOP) is flexible, allowing you to modify your design as your game evolves. As you write more code, you might find that new objects are necessary, or some you initially considered may not be needed after all.

    Key Questions to Guide Your Design

    As you work through this process, consider the following questions to guide your object design:

    1. How many objects can you identify in the example? Look closely at the example game screen provided in Figure 1 of Lesson 5. How many distinct elements can you identify that might need to be treated as objects? These could include characters like your ship, the enemies, a shot, or even the score. Everything you see has a purpose in the game. Take a moment to list them out and think about what each element represents.
    2. What names would you choose for these objects? Think about what each object is and what it does. For example, if your game includes a spaceship, the object representing it might be called Ship. If there are enemies, you might have an object called Enemy. Choosing clear and descriptive names from the start will help your code stay organized and easier to understand.
    3. How do these objects interact with each other? Once you have identified and named your objects, think about how they interact. How does your ship shoot at enemies? How do enemies react when hit? Considering these interactions early on will give you a clearer idea of how each object contributes to the overall functionality of your game.

    Naming and Organizing Your Objects

    An important part of designing objects is choosing meaningful names. The names you pick should make it clear what each object is and what it does in your game. At this stage, it is best to keep things clear and simple. For example, if you are designing the object that represents the player’s ship, use a name that clearly describes it, like Ship. Similarly, for enemies, choose a name that makes it obvious what the object represents.

    For other objects, consider their role and responsibility. What would you call the object that represents something the player shoots? And what about the object that tracks the score? Remember, it is better to use simple, intuitive names that describe the object’s function rather than complicating things with complex names.

    Do not worry if the names are not perfect at first. The most important thing is clarity. You can always refine them as your game evolves. In Squeak, renaming objects is easy, so you do not need to worry about getting everything right in the beginning.

    Final Thoughts

    In object-oriented programming, the process of designing and refining your objects is ongoing. You do not need to have all the objects figured out from the start, and it is okay if things are not perfect right away. The goal is to focus on understanding what each object does and how it interacts with others to create the overall game experience. Over time, you will continue to refine and expand your design.

    Remember that in Smalltalk, making changes to your objects is simple – whether that involves adding new objects, renaming them, or adjusting how they behave. Do not be afraid to iterate and improve as you go along. It is all part of the learning process!

    Good luck as you begin designing your space shooter game. Be sure to refer back to the example game screen shown in Figure 1 as well as the rest of Lesson 5 in the online lesson or the downloadable PDF as you proceed.

    Lesson Resources

    For Lesson 5 and the complete series of lessons on creating the Shooter Game, including all the necessary resources such as PDFs, source code, images, sound file, and more, visit https://scottgibson.site/ShooterGame/. This site provides everything you need to progress and also lets you play the game directly in your browser, seamlessly powered by SqueakJS. Whether you are just getting started with Squeak/Smalltalk or advancing your skills, these resources will help guide you as you move forward through the game development process.

    ← Lesson 4

    Lesson 6 →

    Have a great time with Smalltalk and keep on Squeaking!

  • Lesson 4: Programming the Shooter Game in Squeak/Smalltalk

    Lesson 4: Programming the Shooter Game in Squeak/Smalltalk

    Lesson 4: Using Cascades in Code

    This lesson will be the last introductory lesson (lesson practices) before we begin the actual game creation.

    This lesson is simple and quick, but it introduces cascades, which are commonly used in Smalltalk code. Understanding and becoming familiar with them will help you utilize them effectively, as well as recognize them when you encounter other Smalltalk code. By using cascades, you can reduce code clutter and minimize the amount of typing needed.

    The following code is an example from Lesson 3. This code completes messages by using a period which in Smalltalk is the statement separator. Placing a period between two expressions turns them into independent statements.

    s := SimpleButtonMorph new.
    s label: ‘Move right’.
    s target: moveRight.
    s actionSelector: #value.
    s openInWorld.

    The following code is the example from Lesson 4 using cascades.

    s := SimpleButtonMorph new
    label: ‘Move right’;
    target: moveRight;
    actionSelector: #value;
    openInWorld.

    Even though the code looks simpler, it is important to understand what is happening. When the same object is the receiver of a sequence of consecutive messages, you do not need to repeat it. You can remove the repeated receiving object and replace the ending period with a semicolon (;). So, the basic rules for cascades are:

    • Cascaded expressions are separated by semicolons
    • All cascaded messages share the same receiver as the last message executed before the first semicolon

    So, if it is as simple as replacing periods with semicolons, why does this lesson’s example not work if a semicolon were placed after “SimpleButtonMorph new”?

    SimpleButtonMorph is a class, not an instance of that class. This means that you cannot send instance messages directly to the class itself. A class can receive class messages, but in this example, we are sending instance messages, which can only be sent to instances of the class, not the class itself. Therefore, to interact with the instance, you must first create an instance by sending the message “new” to SimpleButtonMorph. It is this instance of SimpleButtonMorph that can receive instance messages. In other words, all the cascaded messages are sent to the object created by “SimpleButtonMorph new”, demonstrating how a sequence of cascaded messages can be sent to the result of an expression.

    In conclusion, understanding and using cascades in Smalltalk can greatly simplify your code, making it more readable and reducing redundancy. By chaining multiple messages to the same object in a single expression, you can streamline your code and focus on the logic rather than repetitive syntax. With this knowledge, you can write more efficient, elegant Smalltalk code and recognize cascading patterns in other code you encounter.

    For Lesson 4 and the complete series of lessons on creating the Shooter Game, including all the necessary resources such as PDFs, source code, images, sound file, and more, visit https://scottgibson.site/ShooterGame/. This site not only provides everything you need to progress but also allows you to play the game directly in your browser using SqueakJS. Whether you are just getting started with Squeak/Smalltalk or advancing your skills, these resources will help guide you as you move forward through the game development process.

    ← Lesson 3

    Lesson 5 →

    Have a great time with Smalltalk and keep on Squeaking!

  • Lesson 3: Programming the Shooter Game in Squeak/Smalltalk

    Lesson 3: Programming the Shooter Game in Squeak/Smalltalk

    Lesson 3: Moving a Morph with Code

    In this lesson, we will learn about blocks in Smalltalk. A block is a small piece of code that can be treated as an object. It is often used to perform actions or calculations when needed. Blocks are written inside square brackets, and they can be passed around or executed by other parts of the program. While blocks are commonly used in programs to make things happen, for now, think of them as a way to understand how code can be organized and applied. This lesson is a simple introduction to blocks, so you do not need to fully understand everything about them yet. By the end of the lesson, you will have a better idea of what blocks are and how they work in code. You will also learn how to use blocks to interact with your EllipseMorph.

    We will also use a simple button morph to interact with our EllipseMorph. By clicking the button, you will be able to make the EllipseMorph move. This lesson will show you how to create a simple graphical button that can then be used to interact with your morph. This is a nice way of interacting with the morph without having to do much coding for now. It allows you to focus on understanding the basic concepts before diving into more complex programming. As you progress, you will learn how to build more advanced interactions and customize the behavior of your morphs.

    Additional Resources

    For additional learning, there are several resources that can help you dive deeper into the topics we covered. You can start by exploring the Block Swiki page here to get a better understanding of how blocks work in Smalltalk. If you want to learn more specifically about the BlockClosure class, check out a detailed explanation here, also a Swiki article. Another helpful resource is the Terse Guide to Squeak online, which is always available within the Squeak image under Help -> Terse Guide to Squeak. Lastly, the Squeak by Example book is an excellent resource for exploring Squeak and Smalltalk in more detail, and you can read it here. These resources will provide you with more in-depth information and examples to support your learning.

    For the complete series of lessons on creating the Shooter Game, including all the necessary resources like PDFs, source code, images, sound files, and more, visit https://scottgibson.site/ShooterGame/. This site not only offers everything you need to progress but also lets you play the game directly in your browser using SqueakJS. Whether you are just getting started with Squeak/Smalltalk or are advancing your skills, these resources will help guide you as you progress through the game development process.

    ← Lesson 2

    Lesson 4 →

    Have a great time with Smalltalk and keep on Squeaking!

  • Introduction/Lesson 1: Programming the Shooter Game in Squeak/Smalltalk

    Introduction/Lesson 1: Programming the Shooter Game in Squeak/Smalltalk

    Introduction to the Series

    This article kicks off a series designed to introduce programming to beginners through the creation of a simplified space shooter game using Squeak, an open-source implementation of the Smalltalk programming language. By breaking down the process into a series of manageable lessons, the aim is to provide an accessible and interactive entry point into the world of programming. This series will guide learners through the process of building a game from the ground up while introducing them to essential programming concepts along the way. Upon completion, and with the accompanying resources such as source code, images, and a sound file, students will have everything they need to recreate or enhance the game.

    Who This Series is For

    The intended audience for this article and the accompanying series includes both young learners and adults who are new to coding or to Smalltalk. Whether you are a student, educator, or hobbyist, these lessons are tailored to make programming approachable and enjoyable. Throughout the series, we will dive into key programming principles – such as object-oriented design, the concept of “Morphs” in Squeak, and more – at a beginner-friendly pace. Each lesson is supplemented with practical examples. If you are interested in starting with something fun and educational, and you are curious about how games are made or how Smalltalk can be used in a modern development environment, this series is for you.

    Why a Game, and Why Squeak/Smalltalk?

    So why a game, and why in Squeak/Smalltalk? Why not? Everybody understands the domain of games, or gaming. That is, the mechanics, interactions, and goals – such as managing player input, controlling game characters, defining win/loss conditions, and creating interactive environments. Games are a universal medium that spans across ages and cultures, from simple board games to complex video games. This familiarity makes games an excellent starting point for teaching programming concepts, as the mechanics and goals are intuitive to most people. Moreover, games require a variety of programming elements to function, such as managing user input, handling graphics, implementing game rules, designing levels, and even creating sound and music. These components provide a rich environment for introducing and practicing key programming skills – like decision-making, loops, object-oriented design, and event handling – while keeping learners engaged with a fun, practical outcome.

    Why Squeak/Smalltalk is the Right Tool

    Squeak makes all of this very easy, and you do not need to learn anything more than Smalltalk to get started. The language is intuitive and enjoyable to use, and Squeak provides a powerful and engaging development environment. While games may not balance your bank account, they can serve as an excellent resource for learning programming or a new language. Squeak/Smalltalk, in particular, makes this process both accessible and enjoyable.

    How This Series Came to Be

    This article introduces a series of lessons based on a simplified version of a space shooter game I developed using Squeak. The project, which was both fun to create and my first full Squeak program, turned out to be an ideal way to teach my middle school-aged son Smalltalk, as well as the fundamentals of object-oriented programming (OOP). Although he had prior programming experience, he quickly grasped the language due to its simplicity and the interactive nature of the environment. The natural syntax of Smalltalk, combined with the user-friendly environment, not only made it easier for him to solve problems but also allowed him to be more creative, without needing to alter his natural problem-solving approach. Both the language and the environment “got out of his way,” enabling him to express himself more easily and effectively.

    What Will Be Covered in the Series

    The lessons in this series are designed to introduce key programming concepts – such as classes, methods, debugging, and user interface design – through the process of building and modifying a game. You can find the complete list of lessons on the Shooter Game site. Each lesson was written daily, and I discussed topics both before and during the lesson to provide additional detail and ensure a deeper understanding. This approach allowed me to offer relevant explanations exactly when they were needed, based on my son’s progress and evolving needs.

    For each article, I will aim to provide additional helpful information that may not be included in the lessons themselves. If you feel any details are missing or could be useful, please let me know, and I would be happy to provide further information.

    Interactive, Live Coding Approach

    The hands-on, live coding approach in these lessons encourages learners to experiment and learn in real time, making the process both educational and enjoyable. Each lesson also comes with a downloadable PDF version of the lesson page for easy offline reference or printing. The entire series progressively builds upon itself, allowing learners to gradually develop their programming skills as they move through the lessons.

    Lesson 1: Creating and Positioning Morphs

    For today’s lesson, we will dive into the first step in building our game: “Creating and Positioning Morphs.” In this lesson, we will introduce the concept of a Morph and explore how to create and manipulate these visual objects within the Squeak environment. Understanding Morphs is a crucial part of game development in Squeak, as they serve as the foundation for all the interactive elements of the game.

    What is a Morph?

    In Squeak, a Morph is an interactive graphical object. Like everything in Smalltalk, a Morph can be interacted with through messages. It is not a static, lifeless image on the screen, but rather a lively object waiting to interact with its environment. You can send a message to a Morph to receive information about it or to perform an operation. Everything you see when running Squeak is a Morph object. This presents some very exciting capabilities, as it provides you with the ability to create graphical objects, which can interact with the world (the entire Squeak environment – its display screen in this case) and the world can interact with them.

    The Squeak world works using a coordinate system. The coordinate values can be absolute or relative. Each coordinate value is represented as a point, which has an X coordinate and a Y coordinate. For example, a Squeak world (remember, this will be the full size of the display screen in the Squeak environment) with a display size of 1024×768:

    • The point 0@0 is the top-left corner of the screen.
    • The point 0@768 is the lower-left corner of the screen.
    • The point 1024@768 is the lower-right corner of the screen.
    • The point 1024@0 is the top-right corner of the screen.

    Every point in between represents a location within the world. Points can exist outside of that world too; however, they would not be visible.

    In this game, everything is a subclass of Morph, so you will be using Morphs a lot.

    Before beginning Lesson 1, it would be very helpful to read Chapter 1 of the Squeak By Example book (available as a free PDF, SBE-6.0.pdf), an excellent resource for learning Squeak and understanding its environment. Afterward, you can go straight to the lesson here.

    Additional Resources

    To access the full series of lessons and resources for the space shooter game, Shooter Game, visit the lesson site at https://scottgibson.site/ShooterGame/. There, you will find the complete set of lessons and their associated PDFs, along with the source code, images, the sound file, and other useful resources. You can even play the game directly in your browser (using the awesome SqueakJS!). Whether you are a beginner or looking to learn more about Squeak/Smalltalk, its environment, and its tools, these resources will guide you through each step and provide everything you need to recreate or enhance the game.

    Lesson 2 →

    Have a great time with Smalltalk and keep on Squeaking!