Methods continued

You can declare a method on non-struct types, too.

In this example we see a numeric type MyFloat with an Abs method.

You can only declare a method with a receiver whose type is defined in the same package as the method. You cannot declare a method with a receiver whose type is defined in another package (which includes the built-in types such as int).

methods-continued.go

package main
import (
    "fmt"
    "math"
)
type MyFloat float64
func (f MyFloat) Abs() float64 {
    if f < 0 {
        return float64(-f)
    }
    return float64(f)
}
func main() {
    f := MyFloat(-math.Sqrt2)
    fmt.Println(f.Abs())
}