We assume that you are reading this book because you have encountered situations where you have had the same design requirement multiple times, or seen a repetitive problem that has always been solved with the same solution. Those design solutions that are applied again and again to the same type of problem are also known as design patterns.
To better understand the application of design patterns in everyday life, let's take a look at the example of the ATM machine. Every ATM machine needs to have a slot where an ATM card can be inserted, there is a keypad to enter a secret pin, and there is a panel from where the cash can be dispensed. This core functionality of an ATM machine can be considered as a design pattern. Some banks need extra functionalities, such as bill pay or mobile recharge, and they can simply extend this design pattern as per their requirements.
No one would like to reinvent the wheel if an industry-proven solution already exists for a problem, and using such a proven solution would save them time and effort. Furthermore, it also ensures a scalable, robust, and future-ready solution.
In this book, we will discuss the challenges in application development using Apex, common repetitive problems, and most accepted solutions. We have structured our content considering the Apex development platform and blended it with day-to-day challenges that we face during development.
We will first explain the common concepts of application development, which are the building blocks for design patterns. Understanding these concepts is very important as all the design patterns are combinations of one or more principles explained in a later section.
It is not necessary that design patterns should fulfill all requirements so why can't we innovate our own better solution?
Yes, innovation is necessary; and certainly, we can come up with a better design and solution or even a new design pattern. Let's take the preceding example; instead of entering a secret pin, a user can use voice recognition for authentication purposes'. It may look cool to some people, but for many it may be a security concern. Speech recognition may not work because of different accents and so on. My point here is that innovation comes at a cost. In software industry, we don't always have the privilege of time because of project timelines and other dependencies.
Design patterns are age-tested and recommended techniques to address a given problem. They not only help in solving the problem at hand, but also address various possible offshoots of the central problem. Design patterns have also evolved as per requirements and will continue to do so.