golang 方法值接受者和指针接受者区别

package main

import "log"

type Car interface {
	Driving()
	Brake()
}

type BMWCar struct {
	Name string
}

func (b BMWCar) Driving() {
	log.Printf("%s driving", b.Name)
}

func (b BMWCar) Brake() {
	log.Printf("%s brake", b.Name)
}

func (b BMWCar) ChangeName(name string) {
	b.Name = name
}

type BenzCar struct {
	Name string
}

func (b *BenzCar) Driving() {
	log.Printf("%s driving", b.Name)
}

func (b *BenzCar) Brake() {
	log.Printf("%s brake", b.Name)
}

func (b *BenzCar) ChangeName(name string) {
	b.Name = name
}

func main() {
	// 实现了接收者是值类型的方法，会隐含地也实现了接收者是指针类型的方法
	var bmw1 Car = BMWCar{Name: "bmw car"}
	bmw1.Driving()
	bmw1.Brake()

	var bmw2 Car = &BMWCar{Name: "bmw car"}
	bmw2.Driving()
	bmw2.Brake()

	var benz1 Car = &BenzCar{Name: "benz car"}
	benz1.Driving()
	benz1.Brake()

	// 仅仅定义了指针接受者，不会隐含地也实现了接收者是值类型的方法
	// error: cannot use BenzCar{} (value of type BenzCar) as type Car in variable declaration: BenzCar does not implement Car (Brake method has pointer receiver)
	// var benz2 Car = BenzCar{}
	// benz2.Driving()
	// benz2.Brake()

	// 定义：如果方法的接收者是值类型，无论调用者是对象还是对象指针，修改的都是对象的副本，不影响调用者
	/**==== change name ====**/
	/** output
	bmw car driving
	bmw car brake
	*/
	var bmw3 = BMWCar{Name: "bmw car"}
	bmw3.ChangeName("new bmw car")
	bmw3.Driving()
	bmw3.Brake()

	/** output
	bmw car driving
	bmw car brake
	*/
	var bmw4 Car = &BMWCar{Name: "bmw car"}
	bmw3.ChangeName("new bmw car")
	bmw4.Driving()
	bmw4.Brake()

	// 定义： 如果方法的接收者是指针类型，则调用者修改的是指针指向的对象本身
	/**==== change name ====**/
	/** output
	new benz car driving
	new benz car brake
	*/
	benz3 := BenzCar{Name: "bmw car"}
	benz3.ChangeName("new benz car")
	benz3.Driving()
	benz3.Brake()

	/** output
	new benz car driving
	new benz car brake
	*/
	benz4 := BenzCar{Name: "bmw car"}
	benz4.ChangeName("new benz car")
	benz4.Driving()
	benz4.Brake()
}