Object-Oriented Python: Master OOP by Building Games and GUIs

Title Page....13

Copyright....14

Dedication....16

About the Author....17

Acknowledgments....18

Introduction....20

Who Is This Book For?....22

Python Version(s) and Installation....22

How Will I Explain OOP?....24

What’s in the Book....24

Development Environments....27

Widgets and Example Games....27

Part I: Introducing Object-oriented Programming....29

Chapter 1: Procedural Python Examples....30

Higher or Lower Card Game....31

Representing the Data....31

Implementation....32

Reusable Code....35

Bank Account Simulations....35

Analysis of Required Operations and Data....36

Implementation 1—Single Account Without Functions....36

Implementation 2—Single Account with Functions....39

Implementation 3—Two Accounts....42

Implementation 4—Multiple Accounts Using Lists....44

Implementation 5—List of Account Dictionaries....47

Common Problems with Procedural Implementation....50

Object-Oriented Solution—First Look at a Class....51

Summary....52

Chapter 2: Modeling Physical Objects with Object-Oriented Programming....54

Building Software Models of Physical Objects....55

State and Behavior: Light Switch Example....55

Classes, Objects, and Instantiation....60

Writing a Class in Python....61

Scope and Instance Variables....63

Differences Between Functions and Methods....65

Creating an Object from a Class....65

Calling Methods of an Object....67

Creating Multiple Instances from the Same Class....68

Python Data Types Are Implemented as Classes....70

Definition of an Object....71

Building a Slightly More Complicated Class....71

Representing a More Complicated Physical Object as a Class....74

Passing Arguments to a Method....80

Multiple Instances....82

Initialization Parameters....84

Classes in Use....86

OOP as a Solution....87

Summary....88

Chapter 3: Mental Models of Objects and the Meaning of “self”....89

Revisiting the DimmerSwitch Class....89

High-Level Mental Model #1....91

A Deeper Mental Model #2....92

What Is the Meaning of “self”?....97

Summary....101

Chapter 4: Managing Multiple Objects....103

Bank Account Class....103

Importing Class Code....106

Creating Some Test Code....108

Creating Multiple Accounts....108

Multiple Account Objects in a List....111

Multiple Objects with Unique Identifiers....113

Building an Interactive Menu....116

Creating an Object Manager Object....118

Building the Object Manager Object....120

Main Code That Creates an Object Manager Object....123

Better Error Handling with Exceptions....126

try and except....126

The raise Statement and Custom Exceptions....127

Using Exceptions in Our Bank Program....128

Account Class with Exceptions....128

Optimized Bank Class....130

Main Code That Handles Exceptions....132

Calling the Same Method on a List of Objects....134

Interface vs. Implementation....136

Summary....136

Part II: Graphical User interfaces with Pygame....138

Chapter 5: Introduction to Pygame....139

Installing Pygame....140

Window Details....141

The Window Coordinate System....142

Pixel Colors....147

Event-Driven Programs....148

Using Pygame....150

Bringing Up a Blank Window....151

Drawing an Image....155

Detecting a Mouse Click....158

Handling the Keyboard....162

Creating a Location-Based Animation....167

Using Pygame rects....170

Playing Sounds....174

Playing Sound Effects....174

Playing Background Music....175

Drawing Shapes....177

Reference for Primitive Shapes....180

Summary....183

Chapter 6: Object-Oriented Pygame....184

Building the Screensaver Ball with OOP Pygame....184

Creating a Ball Class....185

Using the Ball Class....187

Creating Many Ball Objects....189

Creating Many, Many Ball Objects....191

Building a Reusable Object-Oriented Button....192

Building a Button Class....193

Main Code Using a SimpleButton....196

Creating a Program with Multiple Buttons....198

Building a Reusable Object-Oriented Text Display....200

Steps to Display Text....200

Creating a SimpleText Class....201

Demo Ball with SimpleText and SimpleButton....203

Interface vs. Implementation....205

Callbacks....206

Creating a Callback....207

Using a Callback with SimpleButton....208

Summary....211

Chapter 7: Pygame GUI Widgets....213

Passing Arguments into a Function or Method....213

Positional and Keyword Parameters....215

Additional Notes on Keyword Parameters....216

Using None as a Default Value....218

Choosing Keywords and Default Values....219

Default Values in GUI Widgets....220

The pygwidgets Package....220

Setting Up....222

Overall Design Approach....222

Adding an Image....224

Adding Buttons, Checkboxes, and Radio Buttons....225

Text Output and Input....229

Other pygwidgets Classes....232

pygwidgets Example Program....233

The Importance of a Consistent API....234

Summary....235

Part III: Encapsulation, Polymorphism, and Inheritance....236

Chapter 8: Encapsulation....237

Encapsulation with Functions....237

Encapsulation with Objects....238

Objects Own Their Data....239

Interpretations of Encapsulation....240

Direct Access and Why You Should Avoid It....240

Strict Interpretation with Getters and Setters....246

Safe Direct Access....248

Making Instance Variables More Private....249

Implicitly Private....249

More Explicitly Private....250

Decorators and @property....251

Encapsulation in pygwidgets Classes....256

A Story from the Real World....257

Abstraction....258

Summary....262

Chapter 9: Polymorphism....263

Sending Messages to Real-World Objects....264

A Classic Example of Polymorphism in Programming....264

Example Using Pygame Shapes....266

The Square Shape Class....267

The Circle and Triangle Shape Classes....269

The Main Program Creating Shapes....272

Extending a Pattern....274

pygwidgets Exhibits Polymorphism....275

Polymorphism for Operators....276

Magic Methods....277

Comparison Operator Magic Methods....278

A Rectangle Class with Magic Methods....280

Main Program Using Magic Methods....282

Math Operator Magic Methods....285

Vector Example....285

Creating a String Representation of Values in an Object....288

A Fraction Class with Magic Methods....291

Summary....295

Chapter 10: Inheritance....297

Inheritance in Object-Oriented Programming....298

Implementing Inheritance....300

Employee and Manager Example....301

Base Class: Employee....301

Subclass: Manager....302

Test Code....305

The Client’s View of a Subclass....306

Real-World Examples of Inheritance....308

InputNumber....308

DisplayMoney....312

Example Usage....315

Multiple Classes Inheriting from the Same Base Class....319

Abstract Classes and Methods....324

How pygwidgets Uses Inheritance....329

Class Hierarchy....332

The Difficulty of Programming with Inheritance....334

Summary....335

Chapter 11: Managing Memory Used by Objects....337

Object Lifetime....337

Reference Count....338

Garbage Collection....346

Class Variables....346

Class Variable Constants....347

Class Variables for Counting....348

Putting It All Together: Balloon Sample Program....349

Module of Constants....353

Main Program Code....354

Balloon Manager....357

Balloon Class and Objects....360

Managing Memory: Slots....364

Summary....367

Part IV: Using OOP in Game Development....368

Chapter 12: Card Games....370

The Card Class....371

The Deck Class....374

The Higher or Lower Game....377

Main Program....377

Game Object....379

Testing with __name__....383

Other Card Games....385

Blackjack Deck....385

Games with Unusual Card Decks....385

Summary....386

Chapter 13: Timers....387

Timer Demonstration Program....388

Three Approaches for Implementing Timers....389

Counting Frames....389

Timer Event....390

Building a Timer by Calculating Elapsed Time....392

Installing pyghelpers....394

The Timer Class....395

Displaying Time....398

CountUpTimer....399

CountDownTimer....403

Summary....404

Chapter 14: Animation....405

Building Animation Classes....405

SimpleAnimation Class....406

SimpleSpriteSheetAnimation Class....411

Merging Two Classes....417

Animation Classes in pygwidgets....417

Animation Class....418

SpriteSheetAnimation Class....420

Common Base Class: PygAnimation....422

Example Animation Program....423

Summary....425

Chapter 15: Scenes....427

The State Machine Approach....427

A pygame Example with a State Machine....430

A Scene Manager for Managing Many Scenes....438

A Demo Program Using a Scene Manager....439

The Main Program....442

Building the Scenes....444

A Typical Scene....448

Rock, Paper, Scissors Using Scenes....450

Communication Between Scenes....455

Requesting Information from a Target Scene....456

Sending Information to a Target Scene....457

Sending Information to All Scenes....457

Testing Communications Among Scenes....458

Implementation of the Scene Manager....458

run() Method....460

Main Methods....462

Communication Between Scenes....463

Summary....465

Chapter 16: Full Game: Dodger....467

Modal Dialogs....467

Yes/No and Alert Dialogs....468

Answer Dialogs....472

Building a Full Game: Dodger....475

Game Overview....475

Implementation....476

Extensions to the Game....500

Summary....501

Chapter 17: Design Patterns and Wrap-Up....502

Model View Controller....502

File Display Example....503

Statistical Display Example....504

Advantages of the MVC Pattern....510

Wrap-Up....512

Index....514

Object-Oriented Python is an intuitive and thorough guide to mastering object-oriented programming from the ground up. You’ll cover the basics of building classes and creating objects, and put theory into practice using the pygame package with clear examples that help visualize the object-oriented style. You’ll explore the key concepts of object-oriented programming — encapsulation, polymorphism, and inheritance — and learn not just how to code with objects, but the absolute best practices for doing so. Finally, you’ll bring it all together by building a complex video game, complete with full animations and sounds. The book covers two fully functional Python code packages that will speed up development of graphical user interface (GUI) programs in Python.