Simple: Design Patterns em Scala: Command

Command: Command.scala

package scala.behavioral

import scala.collection.jcl.ArrayList

// Generic/Abstract objects

trait Command[V] {
 val parameters = new ArrayList[Any]()

 // throw an exception if invalid parameters
 def validate() {}

 def execute() : V

 def addParameters(params:Any*) {
  this.parameters ++ params
 }
}

trait SimpleCommand extends Command[Any] {
 def execute() : Any
}

// Composite
trait CompoundCommand[V] extends Command[ArrayList[V]] {
 val commands = new ArrayList[Command[V]]()

 override def validate() {
  for(command <- commands)
   command.validate()
 }
  
  override def execute() : ArrayList[V] = {
    var result = new ArrayList[V]()
    for(command <- commands)
      result.add(command.execute())
    return result
  }
  
}

trait SimpleCompoundCommand extends CompoundCommand[Any]

// Concrete objects

case class MyValue(val str:String)

class SomeConcreteCommand extends Command[MyValue] {
  override def execute() : MyValue = {
    print("Hello ")
    return new MyValue("SomeConcreteCommand")
  }
}

class AnotherConcreteCommand extends Command[MyValue] {
  override def execute() : MyValue = {
    println("Command!")
    return new MyValue("AnotherConcreteCommand")
  }
}

class ComplexConcreteCommand extends CompoundCommand[MyValue] {
  commands.add(new SomeConcreteCommand())
  commands.add(new AnotherConcreteCommand())
}

object CommandClient extends Application {
  var c1 = new SomeConcreteCommand()
  var c2 = new AnotherConcreteCommand()
  var c3 = new ComplexConcreteCommand()
  c1.execute()
  c2.execute()
  c3.execute()
}

Simple

Páginas

sábado, 28 de agosto de 2010

Design Patterns em Scala: Command

Nenhum comentário:

Postar um comentário