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

Factory method

The factory method pattern specifies how an object can defer creation of some internal data and leave the actual task of creation for the derived class. It is part of the original Gang of Four book.


Imagine a kid making cookies out of dough. They can do nothing until they invoke the factory method and say, Give me a cutter. So, you provide them with a cookie cutter (the result of the factory method), and they can finally start making cookies. By implementing this approach, you can be flexible and select the appropriate cookie shape for the occasion. Output from the factory method therefore changes the final result.

The functionality of this pattern, as described in the original Design Patterns publication, looks very similar to the dependency injection approach, but implemented with pure object-oriented tools. This section will mostly focus on the original approach, but at the end, I will spend some time modernizing this technique.

The pure GoF example is stored in the folder...