The abstract factory

The abstract factory is another design pattern from the family of factory patterns. The purpose is the same as all factory design patterns—to encapsulate the object creation logic and hide it from the user. The difference is how it is implemented.

The abstract factory design pattern relies on object composition in contrast to inheritance, which is used by the factory method. Here we have a separate object, which provides an interface to create instances of the classes we need.

Class diagram

Let's keep using the preceding SimpleConnection example here. The following diagram shows how the abstract factory is structured:

As we can see from the preceding figure, now we have a hierarchy of factories rather than a method inside our database client. We will be using the abstract DatabaseConnectorFactory in our application and it will be returning the right objects, depending on the actual instance type.

Code example

Let's have a look at our example from the source point of view....