Christophe Herreman www.herrodius.com Adobe Usergroup Belgium 26 january 2008

What is Prana ? An Inversion of Control (IoC) Container for ActionScript 3.0 Based on Java Spring Current release 0.4 (released today) www.pranaframework.org

What is Prana ?

An Inversion of Control (IoC) Container for ActionScript 3.0

Based on Java Spring

Current release 0.4 (released today)

www.pranaframework.org

What is Prana ? Cairngorm support PureMVC support Reflection API Several Utilities

What is Prana ?

Cairngorm support

PureMVC support

Reflection API

Several Utilities

What is Inversion of Control ? Inversion of Control, also known as IOC, is an object-oriented programming principle that can be used to reduce coupling inherent in computer programs.

What is Inversion of Control ?

Inversion of Control, also known as IOC, is an object-oriented programming principle that can be used to reduce coupling inherent in computer programs.

What is Inversion of Control ? Scenario: Class A uses class B to get something done Class A { public function doSomething():* { var b:B = new B(); var somethingDone:* = b.getSomethingDone(); return markAsDone(somethingDone); } } Notice : can’t switch the implementation of B can’t unit test in isolation

What is Inversion of Control ?

Scenario: Class A uses class B to get something done

Class A {

public function doSomething():* {

var b:B = new B();

var somethingDone:* = b.getSomethingDone();

return markAsDone(somethingDone);

}

}

Notice :

can’t switch the implementation of B

can’t unit test in isolation

Types of Inversion of Control ? Dependency Lookup Dependency Pull Contextualized Dependency Lookup Dependency Injection Constructor Injection Setter Injection

Types of Inversion of Control ?

Dependency Lookup

Dependency Pull

Contextualized Dependency Lookup

Dependency Injection

Constructor Injection

Setter Injection

Dependency Pull Class A { public function doSomething():* { var b:B = UberModel.getInstance().b; var somethingDone:* = b.getSomethingDone(); return markAsDone(somethingDone); } } UberModel.getInstance().b = new B(); var a:A = new A(); a.doSomething();

Dependency Pull

Class A {

public function doSomething():* {

var b:B = UberModel.getInstance().b;

var somethingDone:* = b.getSomethingDone();

return markAsDone(somethingDone);

}

}

UberModel.getInstance().b = new B();

var a:A = new A();

a.doSomething();

Contextualized Dependency Lookup Class A { public function doSomething(model:UberModel):* { var somethingDone:* = model.b.getSomethingDone(); return markAsDone(somethingDone); } } var model:UberModel = UberModel.getInstance(); var a:A = new A(); a.doSomething(model);

Contextualized Dependency Lookup

Class A {

public function doSomething(model:UberModel):* {

var somethingDone:* = model.b.getSomethingDone();

return markAsDone(somethingDone);

}

}

var model:UberModel = UberModel.getInstance();

var a:A = new A();

a.doSomething(model);

Constructor Injection Class A { public function A(b:B) { this.b = b; } public function doSomething():* { var somethingDone:* = b.getSomethingDone(); return markAsDone(somethingDone); } } var a:A = new A(new B()); a.doSomething();

Constructor Injection

Class A {

public function A(b:B) {

this.b = b;

}

public function doSomething():* {

var somethingDone:* = b.getSomethingDone();

return markAsDone(somethingDone);

}

}

var a:A = new A(new B());

a.doSomething();

Setter Injection Class A { private var b:B; public function set b(value:B):void { this.b = value; } public function doSomething():* { var somethingDone:* = b.getSomethingDone(); return markAsDone(somethingDone); } } var a:A = new A(); a.b = new B(); a.doSomething();

Setter Injection

Class A {

private var b:B;

public function set b(value:B):void {

this.b = value;

}

public function doSomething():* {

var somethingDone:* = b.getSomethingDone();

return markAsDone(somethingDone);

}

}

var a:A = new A();

a.b = new B();

a.doSomething();

Inversion of Control? Prefer setter injection Type to interfaces !!! Centralized configuration Maintainability Reusability Testability ... Though counter-intuitive at first !

Inversion of Control?

Prefer setter injection

Type to interfaces !!!

Centralized configuration

Maintainability

Reusability

Testability

...

Though counter-intuitive at first !

What is an IoC Container ? Creates and assembles components/objects and manages their lifecycle. Prana uses an XML dialect to define the “application context” (what objects are available and how they are related)

The Application Context // setter injection <objects> <object id=“a” class=“A”> <property name=“b” ref=“b”/> </object> <object id=“b” class=“B”/> </objects> // constructor injection <objects> <object id=“a” class=“A”> <constructor-arg ref=“b”/> </object> <object id=“b” class=“B”/> </objects>

Working with the IoC container <mx:Application xmlns:mx=&quot;http://www.adobe.com/2006/mxml&quot; creationComplete=&quot;onCreationComplete()“> ... private function onCreationComplete():void { _objectsLoader = new XmlObjectDefinitionsLoader(); _objectsLoader.addEventListener(ObjectDefinitionsLoaderEvent.COMPLETE, onObjectDefinitionsLoaderComplete); _objectsLoader.load(&quot;application-context.xml&quot;); } private function onObjectDefinitionsLoaderComplete(event:ObjectDefinitionsLoaderEvent):void { var container:ObjectContainer = _objectsLoader.container; var a:A = container.getObject(“a”); } ... </mx:Application>

Conclusion Objects defined in external XML file Loaded at runtime Managed by container Deploy your application with different configurations without recompiling!

Conclusion

Objects defined in external XML file

Loaded at runtime

Managed by container

Deploy your application with different configurations without recompiling!

Resources www.pranaframework.org www.herrodius.com

Resources

www.pranaframework.org

www.herrodius.com

Questions?