100天精通Golang（基础入门篇）——第19天：深入剖析Go语言中方法（Method）的妙用与实践

func (t Type) methodName(parameter list)(return list) {
}
func funcName(parameter list)(return list){
}

package main
import (  
    "fmt"
)
type Employee struct {  
    name     string
    salary   int
    currency string
}
/*
 displaySalary() method has Employee as the receiver type
*/
func (e Employee) displaySalary() {  
    fmt.Printf("Salary of %s is %s%d", e.name, e.currency, e.salary)
}
func main() {  
    emp1 := Employee {
        name:     "Sam Adolf",
        salary:   5000,
        currency: "$",
    }
    emp1.displaySalary() //Calling displaySalary() method of Employee type
}

package main
import (
  "fmt"
  "math"
)
type Rectangle struct {
  width, height float64
}
type Circle struct {
  radius float64
}
func (r Rectangle) area() float64 {
  return r.width * r.height
}
//该 method 属于 Circle 类型对象中的方法
func (c Circle) area() float64 {
  return c.radius * c.radius * math.Pi
}
func main() {
  r1 := Rectangle{12, 2}
  r2 := Rectangle{9, 4}
  c1 := Circle{10}
  c2 := Circle{25}
  fmt.Println("Area of r1 is: ", r1.area())
  fmt.Println("Area of r2 is: ", r2.area())
  fmt.Println("Area of c1 is: ", c1.area())
  fmt.Println("Area of c2 is: ", c2.area())
}

Area of r1 is:  24
Area of r2 is:  36
Area of c1 is:  314.1592653589793
Area of c2 is:  1963.4954084936207

package main
import (  
    "fmt"
)
type Employee struct {  
    name     string
    salary   int
    currency string
}
/*
 displaySalary() method converted to function with Employee as parameter
*/
func displaySalary(e Employee) {  
    fmt.Printf("Salary of %s is %s%d", e.name, e.currency, e.salary)
}
func main() {  
    emp1 := Employee{
        name:     "Sam Adolf",
        salary:   5000,
        currency: "$",
    }
    displaySalary(emp1)
}

package main
import "fmt"
/* 声明全局变量 */
var g int
func main() {
   /* 声明局部变量 */
   var a, b int
   /* 初始化参数 */
   a = 10
   b = 20
   g = a + b
   fmt.Printf("结果： a = %d, b = %d and g = %d\n", a, b, g)
}

结果： a = 10, b = 20 and g = 30

func (b *Box) SetColor(c Color) {
  b.color = c
}

package main
import (
  "fmt"
)
type Rectangle struct {
  width, height int
}
func (r *Rectangle) setVal() {
  r.height = 20
}
func main() {
  p := Rectangle{1, 2}
  s := p
  p.setVal()
  fmt.Println(p.height, s.height)
}

20 2

package main
import "fmt"
type Human struct {
  name  string
  age   int
  phone string
}
type Student struct {
  Human  //匿名字段
  school string
}
type Employee struct {
  Human   //匿名字段
  company string
}
func (h *Human) SayHi() {
  fmt.Printf("Hi, I am %s you can call me on %s\n", h.name, h.phone)
}
func main() {
  mark := Student{Human{"Mark", 25, "222-222-YYYY"}, "MIT"}
  sam := Employee{Human{"Sam", 45, "111-888-XXXX"}, "Golang Inc"}
  mark.SayHi()
  sam.SayHi()
}

Hi, I am Mark you can call me on 222-222-YYYY
Hi, I am Sam you can call me on 111-888-XXXX

package main
import "fmt"
type Human struct {
  name  string
  age   int
  phone string
}
type Student struct {
  Human  //匿名字段
  school string
}
type Employee struct {
  Human   //匿名字段
  company string
}
//Human定义method
func (h *Human) SayHi() {
  fmt.Printf("Hi, I am %s you can call me on %s\n", h.name, h.phone)
}
//Employee的method重写Human的method
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) //Yes you can split into 2 lines here.
}
func main() {
  mark := Student{Human{"Mark", 25, "222-222-YYYY"}, "MIT"}
  sam := Employee{Human{"Sam", 45, "111-888-XXXX"}, "Golang Inc"}
  mark.SayHi()
  sam.SayHi()
}

Hi, I am Mark you can call me on 222-222-YYYY
Hi, I am Sam, I work at Golang Inc. Call me on 111-888-XXXX

type Sayer interface {
    Say() string
}
type Dog struct {
}
func (d Dog) Say() string {
    return "Woof!"
}
type Cat struct {
}
func (c Cat) Say() string {
    return "Meow!"
}
func AnimalTalk(s Sayer) {
    fmt.Println(s.Say())
}
func main() {
    var d Sayer = Dog{}
    var c Sayer = Cat{}
    AnimalTalk(d)
    AnimalTalk(c)
}

type Geometry interface {
    Area() float64
    Perimeter() float64
}
type Square struct {
    side float64
}
func (s Square) Area() float64 {
    return s.side * s.side
}
func (s Square) Perimeter() float64 {
    return 4 * s.side
}

type Greeter struct {
    Name string
}
func (g Greeter) Greet() {
    fmt.Println("Hello", g.Name)
}
func main() {
    greet := Greeter{Name: "John"}.Greet
    greet()
}

type Adder struct {
    Base int
}
func (a Adder) Add(x int) int {
    return a.Base + x
}
func main() {
    add := Adder{Base: 2}.Add
    fmt.Println(add(3)) // Output: 5
}

package geometry
type Rectangle struct {
    Length, Width float64
}
func (r Rectangle) Area() float64 {
    return r.Length * r.Width
}
func (r Rectangle) perimeter() float64 {
    return 2 * (r.Length + r.Width)
}