Book Image

Hands-On Design Patterns with Delphi

By : Primož Gabrijelčič
Book Image

Hands-On Design Patterns with Delphi

By: Primož Gabrijelčič

Overview of this book

Design patterns have proven to be the go-to solution for many common programming scenarios. This book focuses on design patterns applied to the Delphi language. The book will provide you with insights into the language and its capabilities of a runtime library. You'll start by exploring a variety of design patterns and understanding them through real-world examples. This will entail a short explanation of the concept of design patterns and the original set of the 'Gang of Four' patterns, which will help you in structuring your designs efficiently. Next, you'll cover the most important 'anti-patterns' (essentially bad software development practices) to aid you in steering clear of problems during programming. You'll then learn about the eight most important patterns for each creational, structural, and behavioral type. After this, you'll be introduced to the concept of 'concurrency' patterns, which are design patterns specifically related to multithreading and parallel computation. These will enable you to develop and improve an interface between items and harmonize shared memories within threads. Toward the concluding chapters, you'll explore design patterns specific to program design and other categories of patterns that do not fall under the 'design' umbrella. By the end of this book, you'll be able to address common design problems encountered while developing applications and feel confident while building scalable projects.
Table of Contents (18 chapters)
Title Page
Copyright and Credits
About Packt
Contributors
Preface
Index

Event-driven programming


Creating applications by writing event handlers is a basic tenet of rapid application development with Delphi. From responding to button clicks to reacting to an application being resized, from overriding paint mechanisms to writing code that executes when the application is idle everything is done by writing event handlers.

Event-driven programming is not a Delphi invention. It was introduced a long time ago with the appearance of the first Graphical User Interface (GUI) libraries. Before this programming paradigm was introduced, programs were written as big ugly loops that checked the position of the mouse against each GUI element, checked whether a button had been pressed, called some code if it was, checked the keyboard, and so on and so on. All in all, creating user interfaces in that manner was extremely slow and boring.

With event-driven programming, all of that is replaced with a similar loop that runs at the heart of your GUI framework library. In Windows...