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

Object pool

The last pattern in this chapter, object pool, is again not part of the original design patterns book. Object pools as a concept appeared early in the history of OOP, but somehow the Gang of Four didn't see them as a design pattern.

Object pool functions as storage for objects. When we have an object that takes a long time to create and initialize, we sometimes don't want to spend time doing it all over again. Instead of destroying such an object, we can simply put it away in a special container: an object pool. Later, we can just ask the object pool to return the already-created object, an operation that's much faster than creating a new object.


If you have to write a letter (yes, a physical one, on paper!), you need a pen. If there is no pen in the house, you will go to the shop and buy one. Acquiring a new pen is therefore a costly operation. Because of that, you don't throw a pen away once you've finished the letter. Instead, you store it in a drawer. The next time you...