Factory Method in Go
Factory method is a creational design pattern which solves the problem of creating product objects without specifying their concrete classes.
Factory Method defines a method, which should be used for creating objects instead of direct constructor call (
new operator). Subclasses can override this method to change the class of objects that will be created.
If you can’t figure out the difference between various factory patterns and concepts, then read our Factory Comparison.
It’s impossible to implement the classic Factory Method pattern in Go due to lack of OOP features such as classes and inheritance. However, we can still implement the basic version of the pattern, the Simple Factory.
In this example, we’re going to build various types of weapons using a factory struct.
First, we create the
iGun interface, which defines all methods a gun should have. There is a
gun struct type that implements the iGun interface. Two concrete guns—
musket—both embed gun struct and indirectly implement all
gunFactory struct serves as a factory, which creates guns of the desired type based on an incoming argument. The main.go acts as a client. Instead of directly interacting with
musket, it relies on
gunFactory to create instances of various guns, only using string parameters to control the production.