If you are a software engineer, you probably have encountered or used the Factory pattern in your projects. But what is it exactly, and why is it useful? In this article, we will explain the basic idea, the benefits, and the types of the Factory pattern in software engineering.
The Factory pattern is a design pattern that provides a way to create objects without specifying the exact class or constructor of the object. Instead, you use a factory method or a factory class that returns an object of a certain interface or abstract class. This way, you can decouple the creation logic from the rest of the code, and make it more flexible and maintainable.
Using the factory pattern it can give you a robust solution for your application by standardized methods to instantiating objects that require some infra in your code. With it you can specify or somehow demonstrate how you solution is meant to be instantiating objects for your specific application issues. It can be an abstraction layer that leverage your solution to be even more testable by abstracting the factories with interfaces and letting it to be possible to replace some parts of your code with mocking objects that let you test the parts that matters for you testing. Factory pattern is a good pattern but requires some experience to get the right way to. so use it where the application requires to instantiate lots of objects..
The Factory pattern offers a range of benefits for software engineering, such as reducing the coupling between the client code and concrete classes of the objects, allowing for new types of objects to be added and changed without affecting the client code, promoting single responsibility, and supporting the principle of open-closed. This makes the code more modular, testable, and extendable without needing to modify existing code.
The Simple Factory is a factory method that takes a parameter that specifies the type of object to create, and returns an object of that type. For example, in Java, you can have a ShapeFactory class that has a createShape method that takes a string as an argument, and returns a Shape object based on the string. The code could look something like this:
public class ShapeFactory {
public Shape createShape(String shapeType) {
if (shapeType == null) {
return null;
}
if (shapeType.equalsIgnoreCase("circle")) {
return new Circle();
}
if (shapeType.equalsIgnoreCase("square")) {
return new Square();
}
if (shapeType.equalsIgnoreCase("rectangle")) {
return new Rectangle();
}
return null;
}
}
The Simple Factory is easy to implement and use, but it has some drawbacks. For example, it can become too complex and hard to maintain if there are many types of objects to create, or if the creation logic involves more parameters or conditions. It also violates the open-closed principle, as you have to modify the factory method every time you add a new type of object.
The Abstract Factory is a factory class that provides an interface for creating a family of related or dependent objects, without specifying their concrete classes. For example, in Java, you can have an AbstractFactory interface that defines methods for creating different types of shapes, and then have concrete subclasses that implement those methods for different scenarios. The code could look something like this:
public interface AbstractFactory {
public Shape createCircle();
public Shape createSquare();
public Shape createRectangle();
}
public class RoundedShapeFactory implements AbstractFactory {
public Shape createCircle() {
return new RoundedCircle();
}
public Shape createSquare() {
return new RoundedSquare();
}
public Shape createRectangle() {
return new RoundedRectangle();
}
}
public class NormalShapeFactory implements AbstractFactory {
public Shape createCircle() {
return new Circle();
}
public Shape createSquare() {
return new Square();
}
public Shape createRectangle() {
return new Rectangle();
}
}
The Abstract Factory is more flexible and scalable than the Simple Factory, as it allows you to create different families of objects without changing the client code, and to add new types of objects by extending the interface and the subclasses. It also supports the open-closed principle, as you can add new types of objects without modifying the existing code.
The Factory design pattern simplifies object creation by providing a uniform interface, concealing specific class details. In literature I found really smart embedded implementations expecially useful in developing interfaces between some classes and bare communication lines. It offers flexibility by allowing code to adapt to different lines, encapsulates object creation complexities and enhances testability by enabling super-easy creation of mock objects for testing. This pattern streamlines software development, ensuring adaptable, modular, and easily testable code interfacing with diverse communication lines.