interface vs struct

A pointer to a struct and a pointer to an interface are not the same.

An interface can store either a struct directly or a pointer to a struct.

• When interface points to a struct, you do not use a pointer to the interface.
• You use the interface directly.

type Fooer interface {
    Dummy()
}

type Foo struct{}

func (f Foo) Dummy() {}

func main() {
    var f1 Foo
    var f2 *Foo = &Foo{}

    DoFoo(f1)
    DoFoo(f2)
}

func DoFoo(f Fooer) {
    fmt.Printf("[%T] %+v\n", f, f)
}

/* output */
// [main.Foo] {}
// [*main.Foo] &{}