QI4j is a composite-oriented programming framework that follows domain-driven design (DDD) principles. It aims to decouple behavior from classes using aspects and dependency injection. Composites allow combining fragments and mixins to encapsulate behavior and state. The example shows defining interfaces for a HelloWorld composite's behavior and state, implementing mixins for each, and running the composite by injecting dependencies and calling methods.

1. QI4j

2. What is
● Framework
● Composite Oriented Programming
● DDD
● Aop
● DI

3. Principles

4. OOP is Class Oriented

5. Behavior Depends on Context

8. Decoupling is Virtue

9. Business Rules matters more

10. Solution

11. Fragments

12. Composite

13. HelloWorld
public interface HelloWorld extends
HelloWorldBehaviour, HelloWorldState {
}

14. Behaviour
@Mixins( HelloWorldBehaviourMixin.class )
public interface HelloWorldBehaviour
{
String say();
}

15. Impl
public class HelloWorldBehaviourMixin
implements HelloWorldBehaviour
{
@This HelloWorldState state;
public String say()
{
return state.getPhrase() + " " + state.getName();
}
}

16. State
@Mixins( HelloWorldStateMixin.class )
public interface HelloWorldState
{
void setPhrase(@NotEmpty String phrase )
throws IllegalArgumentException;
String getPhrase();
void setName( @NotEmpty String name )
throws IllegalArgumentException;
String getName();
}

17. Running
TransientBuilderFactory factory =
assembler.transientBuilderFactory();
HelloWorld olaMundo =
factory.newTransient( HelloWorldComposite.cla
ss );
olaMundo.setName("Jeff");
olaMundo.setPhrase("adoro mac");
System.out.println( olaMundo.say() );