CODEWITHSUNDEEP
pointersgo
lukemh
lukemh

Reputation: 5323

golang method pointer to receiver

I have the following struct and :

type Person struct {
    Name    string
}


steve := Person{Name: "Steve"}

Can you explain how the following 2 methods (one without the pointer and one with in the receiver) both are able to print the p.Name?

func (p *Person) Yell() {
    fmt.Println("Hi, my name is", p.Name)
}

func (p Person) Yell(){
    fmt.Println("YELLING MY NAME IS", p.Name)
}

steve.Yell()

Wouldn't the Name not exist when pointing straight to the Person (not the instance steve?)

Upvotes: 2

Views: 862

Answers (1)

OneOfOne
OneOfOne

Reputation: 99225

Both point to the instance, however (p Person) points to a new copy every time you call the function, where (p *Person) will always point to the same instance.

Check this example : 

func (p Person) Copy() {
    p.Name = "Copy"
}

func (p *Person) Ptr() {
    p.Name = "Ptr"
}

func main() {
    p1, p2 := Person{"Steve"}, Person{"Mike"}
    p1.Copy()
    p2.Ptr()
    fmt.Println("copy", p1.Name)
    fmt.Println("ptr", p2.Name)
}

Also read Effective Go, it's a great resource to the language.

Upvotes: 4

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