Preface

It was spring 2015; we were both discussing our presentation for Dreamforce 2015. During the discussion, we stumbled on the topic of the usage of design patterns in Apex. We observed that design patterns are still not extensively used in the Apex programming arena. We think that a few prominent factors for this situation are that there are not enough resources available around the design pattern implementation in Apex. Secondly, most of the Apex programmers who started their development career with Force.com have less exposure to other development platforms. Thirdly, some of the design patterns simply do not apply to Force.com development platforms.

As per our observation, the usage and mention of design patterns in day-to-day programming is reduced in Apex as compared to other development platforms. Developers coming from other programming backgrounds mostly have a working experience with design patterns and it's implicit for them to use it in their code style and design.

We realized that it would be even better to develop content around the design pattern implementation in a language that Apex developers can easily relate to. We positively think that by providing scenarios that are specific to Apex development use cases, developers will be able to understand and implement the design patterns in Apex with ease.

To ensure that we are able to provide information uniformly to all Apex developers irrespective of their experience level, this book also includes general programming best practices, programming principles, OOP concepts, and the usual pitfalls at appropriate places.

In line with our past experience with design pattern learning and implementation is the problem of memorizing the design patterns and situations where they fit in. However, in this book, we took real-life scenarios to explain a situation where an appropriate design pattern will be applied. One can easily relate the design pattern with an example given in this book to identify when it is the time to use that pattern.

Some open source GitHub repository links, Salesforce official developer blogs, and other tips have been shared throughout the book, which can be very helpful in Force.com project development.

What this book covers

Chapter 1, An Introduction to Apex Design Pattern, covers the basics of inheritance, abstract classes, polymorphism, cohesion and coupling, and object-oriented design principles.

Chapter 2, Creational Patterns, focuses on different ways to instantiate objects to achieve code reusability, ease of maintenance, and loose coupling.

Chapter 3, Structural Patterns, explains the design patterns that can solve many situations and problems, which occur during project development in Apex, that demand a change in functionalities and cause a ripple effect on the rest of the system.

Chapter 4, Behavioral Patterns, provides a glimpse of some problems, such as double dispatch and code maintenance issues, and explains how to use appropriate design patterns to fix them.

Chapter 5, Handling Concurrency in Apex, discusses the design solution for the race condition in concurrency, which can result in data corruption without anyone noticing it.

Chapter 6, Anti-patterns and Best Practices, shows some common pitfalls observed during application development in Apex and suggested solutions.

What you need for this book

We need an Internet-enabled computer that is capable of running modern browsers supported by Salesforce. We can use the developer console in a browser to write the Apex code in Salesforce.

Interested readers can also use their favorite IDEs, such as Sublime Text, Eclipse, Welkins, Atom, Aside, Cloud9, or BrainEngine.

You will also need a free Salesforce developer account to try all the code snippets and examples provided in this book.

Who this book is for

This book is intended for all Apex developers who want to learn and enhance their Apex code designing skills by applying various design patterns. It can be considered as a stepping stone for beginners or intermediate-level Apex programmers by filling their arsenal with powerful design patterns.

Conventions

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Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "The AdminGoldSupportImpl and AdminPlatinumSupportImpl classes are written in the same way."

A block of code is set as follows:

public class Mario {
    public void ability(){
        System.debug('I can Walk');
    }
    public void info(){
        System.debug('I am Mario');
    }
}

Any command-line input or output is written as follows:

$ mkdir css

$ cd css

New terms and important words are shown in bold. 

Note

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