Hands-On Design Patterns with Delphi

By : Primož Gabrijelčič

5 (1)

Buy this Book

Hands-On Design Patterns with Delphi

5 (1)

By: Primož Gabrijelčič

Buy this Book

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.

Preface

Who this book is for

What this book covers

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Section 1: Design Pattern Essentials

Introduction to patterns

Patterns in programming

Patterns are useful

Gang of Four started it all

Pattern taxonomy

Criticism

Anti-patterns

Design principles

Summary

Section 2: Creational Patterns

Singleton, Dependency Injection, Lazy Initialization, and Object Pool

Singleton

Dependency injection

Lazy initialization

Object pool

Summary

Factory Method, Abstract Factory, Prototype, and Builder

Factory method

Abstract factory

Prototype

Builder

Summary

Section 3: Structural Patterns

Composite, Flyweight, Marker Interface, and Bridge

Composite

Flyweight

Marker interface

Bridge

Summary

Adapter, Proxy, Decorator, and Facade

Selecting an appropriate structural pattern

Adapter

Proxy

Decorator

Facade

Summary

Section 4: Behavioral Patterns

Nullable Value, Template Method, Command, and State

Null object

Template method

Command

State

Summary

Iterator, Visitor, Observer, and Memento

Iterator

Visitor

Observer

Memento

Summary

Section 5: Concurrency Patterns

Locking patterns

Delphi idioms – parallel programming

Lock

Lock striping

Double-checked locking

Optimistic locking

Readers-writer lock

Summary

Thread pool, Messaging, Future and Pipeline

Thread pool

Messaging

Future

Pipeline

Summary

Section 6: Miscellaneous Patterns

Designing Delphi Programs

Event-driven programming

Actions

LiveBindings

Form inheritance

Frames

Data modules

Summary

Other Kinds of Patterns

Exceptions

Debugging

Functional programming

Summary

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Memento

The last pattern in this chapter, memento, helps us save and restore a state of a complex object. It was originally introduced by the Gang of Four.

When you want to store and restore a current state of a complex object, you can easily run into problems with encapsulation. There may, for example, exist an internal state that is important for the correct functioning of the object, but is not accessible to the public. In such a case, we may not be able to access this state from the code that is not part of the object.

Even if all internal fields are accessible by the public, accessing internal state from external code is a bad practice. The internal representation of an object may change unexpectedly (for example, with a software update), and if a maintainer of such external code is not aware of that, the program would break.

The memento pattern prescribes how a complex object...