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

Lazy initialization

After two lengthy discussions, a section about a lazy initialization pattern should present a comfortable change. This pattern appeared in the Gang of Four book under the name of virtual proxy, which virtually nobody is using today. Lazy initialization, on the other hand, has become a common household name.

Lazy initialization is a very simple pattern that merely states whether an object is not always required, creating it only when it is needed. We would use this pattern on two occasions: when the creation of an object or its initialization is a slow process, or when the very existence of the object signifies something.


Whenever I go somewhere with a car, I have to take into account the small possibility that the car will not start. If that happens, I call my mechanic. That's lazy initialization. Doing it in a classical object-oriented way would be entirely stupid. Just imagine, I want to go out, and so I call my mechanic and say: Please come here; I intend to start...