内联函数简化抽象工厂

1.通过invoke用inline定义为内联函数，同时引入reified关键字，使用具体化参数类型的语法特性

2.实现

interface Computer

class Dell: Computer

class Asus: Computer

class Acer: Computer

class DellFactory : AbstractFactory(){

override fun produce() = Dell()

}

class AsusFactory : AbstractFactory(){

override fun produce(): Computer = Asus()

}

class AcerFactory : AbstractFactory(){

override fun produce(): Computer = Acer()

}

open abstract class AbstractFactory {

abstract fun produce(): Computer

companion object {

inline operator fun invoke(): AbstractFactory =

when (T::class) {

Dell::class -> DellFactory()

Asus::class -> AsusFactory()

Acer::class -> AcerFactory()

else ->throw IllegalArgumentException()

}

}

}

3.调用

val dellFactory = AbstractFactory<Dell>()

val dell = dellFactory.produce()

本文摘自《Kotlin核心编程》