类和对象—>接口

interface MyInterface { 
    fun bar()
    fun foo() {
        // 可选的方法体
    } 
}

class Child : MyInterface {
     override fun bar() {
        // 方法体
     }
}

interface MyInterface { 
        val prop: Int // 抽象的
        val propertyWithImplementation: String 
                get() = "foo"
        fun foo() {
             print(prop)
        }
}

class Child : MyInterface {
     override val prop: Int = 29
}

interface Named {
    val name: String
}

interface Person : Named {
    val firstName: String
    val lastName: String
    override val name: String get() = "$firstName $lastName"
}

data class Employee( // 不必实现“name”
        override val firstName: String,
        override val lastName: 
        String, val position: Position
) : Person

interface A {
    fun foo() {
        print("A")
    }
    fun bar()
}

interface B {
    fun foo() {
        print("B")
    }
    fun bar() {
        print("bar")
    }
}
class C : A {
    override fun bar() {
        print("bar")
    }
}

class D : A, B {
    override fun foo() {
        super<A>.foo()
        super<B>.foo()
    }
    override fun bar() {
        super<B>.bar()
    }
}