It's the game of the mouse and the cat :-D
We can change the package color like this :
package color
type Color interface {
void()
}
type color struct {
v string
}
func (c color) void() {}
func (c color) String() string {
return c.v
}
var (
Red color = color{"red"}
Green color = color{"green"}
Blue color = color{"blue"}
)
func fn(c color.Color) {
switch c {
case color.Red, color.Green, color.Blue:
log.Printf("c=%#+v -- OK", c)
default:
log.Printf("c=%#+v -- should not be possible", c)
}
}
func main() {
var c color.Color
fn(c)
}
