Dart: Scalable Application Development

Using mixins

In Dart, just like in Ruby, your classes can use mixins to assign a certain behavior to your class. Say an object must be able to store itself, so its class mixes in a class called Persistable that defines save() and load() methods. From then on, the original class can freely use the mixed-in methods. The mechanism is not used for specialized subclassing or is-a relationships, so it doesn't use inheritance. This is good because Dart uses a single inheritance, so you want to choose your unique direct superclass with care.

How to do it...

• Look at the mixins project; the Embrace class from the previous recipe needs to persist itself, so it mixes with the abstract class Persistable, thereby injecting the save and load behavior. Then, we ...