/
TestExtAsMember.kt
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/
TestExtAsMember.kt
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package com.boycoder.kotlinjetpackinaction.chapter.c06
/**
* Created by zhu.tao on 2020/7/31.
*/
open class Base { }
class Derived : Base() { }
open class BaseCaller {
open fun Base.printFunctionInfo() {
println("Base extension function in BaseCaller")
}
open fun Derived.printFunctionInfo() {
println("Derived extension function in BaseCaller")
}
val Derived.test: Int
get() = 1
fun call(b: Base) {
b.printFunctionInfo() // 调用扩展函数
}
}
class DerivedCaller: BaseCaller() {
override fun Base.printFunctionInfo() {
println("Base extension function in DerivedCaller")
}
override fun Derived.printFunctionInfo() {
println("Derived extension function in DerivedCaller")
}
}
/**
* 步骤:先运行代码,然后调试代码,最后反编译代码。
*
* 理解这个例子的关键在于:
*
* BaseCaller().call(), DerivedCaller().call() 是多态的。
*
* 而 call 函数里的 base.printFunctionInfo() 是静态的。
*
* 这段话一定要结合反编译后的代码看
*
*/
fun main() {
BaseCaller().call(Base())
BaseCaller().call(Derived())
DerivedCaller().call(Base())
DerivedCaller().call(Derived())
}