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


The last pattern we described in this chapter is a bit different than the three we described before. The previous patterns were all wrapping one and only one component, while the facade pattern wraps multiple components and subsystems. In addition to that, facade is the only pattern from this chapter that provides a reduced interface and not a full feature set of wrapped components.

As such, a facade represents a front for a complex subsystem. Besides connecting subsystems together, it also provides a problem-specific interface. In fact, if we follow the single responsibility principle, we can implement multiple facades for the same set of subsystems, each providing a very specific interface to solve one specific problem.


When you ask your smart device OK, <insert name>, will it rain today?,  you are accessing a Facade for an incredibly complex system. Your words are first converted to text, and then another subsystem tries to understand your question. The third one provides...