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

Chapter 7. Iterator, Visitor, Observer, and Memento

When your task is writing code that is simple to maintain and test, you strive away from tightly connected parts that know too much about each other. The four patterns that will be described in this chapter will help you write complex code that interacts in different ways but is not interconnected in all possible—and impossible—ways in an unmanageable mess.

Two patterns from this chapter, iterator and observer, are, in my opinion, the two most important patterns from the Gang of Four collection. If you incorporate only two patterns into your code, let them be these two! They both help with decoupling parts of code and programming to the interface, not the implementation; two guidelines that will help you write maintainable code.

That doesn't mean that you should ignore other patterns from this chapter, or from this book! All patterns can be important—you just have to know when and how they should be used. Visitor and Memento are certainly...