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

Selecting an appropriate structural pattern

Distinguishing between the Bridge, adapter, proxy, decorator, and the facade is not always easy. At first glance, both the bridge and the adapter look almost the same, and there is just a small step from a proxy to a decorator, which sometimes looks almost like a facade. To help you select the appropriate pattern, I have put together a few guidelines.


Both the bridge and the adapter design patterns look completely the same. They implement one interface and map it into another. The difference lies in the motivation for using the pattern.

When you define both the abstraction (the public interface) and the implementation (the actual worker object) at the same time, you are creating a bridge. If, however, you already have an existing object that implements an interface and you have to use it in an environment with different expectations, you will write an adapter.

The proxy pattern also looks very similar to both the bridge and the adapter. It, however...