golang之interface（接口）与 reflect 机制

一、概述

　　什么是interface，简单的说，interface是一组method的组合，通过interface来定义对象的一组行为；

　　interface类型定义了一组方法，如果某个对象实现了某个接口的所有方法，则此对象就实现了此接口；

package main

import "fmt"

type Human struct {
    name  string
    age   int 
    phone string
}

type Student struct {
    Human  //匿名函数
    school string
    loan   float32
}

type Employee struct {
    Human
    company string
    money   float32
}

//Human对象实现Sayhi方法
func (h *Human) Sayhi() {
    fmt.Printf("hi, I am %s you can call me on %s\n", h.name, h.phone)
}

//Human对象实现了Sing方法
func (h *Human) Sing(lyrics string) {
    fmt.Println("lalala...", lyrics)
}

//Human对象实现了Guzzle方法
func (h *Human) Guzzle(beerStein string) {
    fmt.Println("Guzzle Guzzle...", beerStein)
}

//Student 实现了BorrowMoney方法
func (s *Student) BorrowMoney(amount float32) {
    s.loan += amount
}

//Empolyee 重载了Human的Sayhi的方法
func (e *Employee) Sayhi() {
    fmt.Printf("hi, I am %s, I work at %s. call me on %s\n", e.name, e.company, e.phone)
}

//Employee实现了SpendSalary的方法
func (e *Employee) SpendSalary(amount float32) {
    e.money -= amount
}

//define interface
/*
type Men interface {
    Sayhi()
    Sing(lyrics string)
    Guzzle(beerStein string)
}

type YoungChap interface {
    Sayhi()
    Sing(song string)
    BorrowMoney(amount float32)
}

type ElderlyGent interface {
    Sayhi()
    Sing(song string)
    SpendSalary(amount float32)
}
*/

//interface Men被Human，Student, Employee都实现
// Student, Employee包含了Human匿名字段，所有也包含了其接口实现
type Men interface {
    Sayhi()
    Sing(lyrics string)
}

func main() {
    mike := Student{Human{"Mike", 24, "22-22-xx"}, "MIT", 0.00}
    paul := Student{Human{"paul", 26, "23-32-xx"}, "Harvard", 5.00}
    sam := Employee{Human{"Sam", 46, "33-33-33"}, "Gling inc", 1000}
    Tom := Employee{Human{"Tom", 33, "33-334-11"}, "Things ltd", 400}

    var i Men //interface type
    i = &mike
    fmt.Println("this is Mike, a Student\n")
    i.Sayhi()
    i.Sing("my name is Mike")

    i = &Tom
    fmt.Println("this is Tom, an employee\n")
    i.Sayhi()
    i.Sing("my name is Tom")

    x := make([]Men, 3)
    x[0], x[1], x[2] = &paul, &sam, &mike
    for _, value := range x {
        value.Sayhi()
    }
}

二、反射机制

package main

import (
    "fmt"
    "reflect"
)

func main() {
    var x float64 = 3.4
    p := reflect.ValueOf(&x)
    v := p.Elem()
    fmt.Println(v)
    v.SetFloat(8.3)
    fmt.Println(v)
}