指针上的golang指针作为函数参数

I have the function

func addCatsToMap(m map[string][]CatHouse, meowId int, treats Set, dog *Dog) {

//if (complicated thing) add Cat to m

}

Is it true that m, treats, and dog are passed-by-reference, and meowId has it's value copied.

Since m is map, its pass-by-reference.

Dog is a struct. So, I should pass the pointer to avoid copying the data.

Set is an interface, as defined here:

type Set interface {
  Add(value string)
  Contains(value string) (bool)
  Length() (int)
  RemoveDuplicates()
}

Is Set pass-by-value?

An interface type is simply a set of methods. Notice that the members of an interface definition do not specify whether or not the receiver type is a pointer. That is because the method set of a value type is a subset of the method set of its associated pointer type. That's a mouthful. What I mean is, if you have the following:

type Whatever struct {
    Name string
}

and you define the following two methods:

func (w *Whatever) Foo() {
    ...
}

func (w Whatever) Bar() {
    ...
}

WhateverBar()*WhateverFoo()Bar()

type Grits interface {
    Foo()
    Bar()
}

*WhateverGritsWhateverWhateverFoo()

The following example illustrates a function that takes an interface type in both ways:

package main

import "fmt"

type Fruit struct {
    Name string
}

func (f Fruit) Rename(name string) {
    f.Name = name
}

type Candy struct {
    Name string
}

func (c *Candy) Rename(name string) {
    c.Name = name
}

type Renamable interface {
    Rename(string)
}

func Rename(v Renamable, name string) {
    v.Rename(name)
    // at this point, we don't know if v is a pointer type or not.
}

func main() {
    c := Candy{Name: "Snickers"}
    f := Fruit{Name: "Apple"}
    fmt.Println(f)
    fmt.Println(c)
    Rename(f, "Zemo Fruit")
    Rename(&c, "Zemo Bar")
    fmt.Println(f)
    fmt.Println(c)
}

Raname(&f, "Jorelli Fruit")Rename(c, "Jorelli Bar")Fruit*FruitRenamable*CandyRenableCandy

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