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


An iterator pattern is used to traverse a container and access its elements. The power of this pattern is that it decouples algorithms from the container implementation. We can then write an algorithm that is coded to the iterator interface and not to the actual implementation of the container. 

Let's say we have two completely different data structures, an array and a linked list. If we need to implement the same algorithm operating on both structures, we have to write two versions of the code. You would access an array with direct addressing and the other would walk the linked list.

On the other hand, if both the array and linked list implement the same interface that allows the algorithm to walk over the data and access all elements, we can write only one version of the algorithm. Instead of working with data structures directly, the algorithm would work with that interface.


An interface in this context means any public interface (a set of methods). It doesn't have to be implemented...