On Tue, Aug 10, 2021 at 12:01 PM E Z <legend...@gmail.com> wrote:
> I feel confused when I use the function pointer which point to the struct
> method. Here is the test code:
>
> /***
> package main
>
> type Zoo struct {
> Animal string
> }
>
> func (z Zoo) Display(){
> fmt.Printf("Current animal is:%s\n", z.Animal)
> }
>
This method has a value receiver. When pf is assigned to gz.Display, it is
assigned with its receiver, which is a copy of gz.
Change the method to func (z *Zoo) Display(), and it will work as you
expect.
>
> func main(){
> gz := &Zoo{
> Animal: "Monkey",
> }
>
> pf := gz.Display
> pf() //display "Current animal
> is Monkey"
> gz.Animal="Tiger"
> pf() //display "Current animal
> is Monkey"
> gz.Display() //display "Current animal is
> Tiger"
> }
> ***/
> As the code is shown above, even though I changed the value of the member
> field of the Zoo instance gz, the function pointer call that followed
> still prints the unmodified value.
>
> Can someone help explain why? In my opinion, The function pointer pf
> should bind to the instance gz and its method(note that gz here is a
> pointer variable), if so anytime I change the value of the variable gz,
> pf should reflect the changes.
>
> Thanks,
> Ethan
>
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