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interfaces01.go
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/
interfaces01.go
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/* RZFeeser | Alta3 Research
Getting at interfaces */
package main
import (
"fmt"
"math"
)
// basic interface for geometric shapes
type geometry interface {
area() float64 // needs an area method that returns a float64
perim() float64 // needs a perim method that returns a float64
}
type rect struct {
width, height float64
}
type circle struct {
radius float64
}
// To implement an interface in Go we just need to implement all the methods in the interface
// Here we implement geometry on rects.
func (r rect) area() float64 {
return r.width * r.height
}
func (r rect) perim() float64 {
return 2*r.width + 2*r.height
}
// the implementation for circle
func (c circle) area() float64 {
return math.Pi * c.radius * c.radius
}
func (c circle) perim() float64 {
return 2 * math.Pi * c.radius
}
// a generic "measure" function taking advantage of the interface "geometry"
func measure(g geometry) {
fmt.Println(g)
fmt.Println(g.area())
fmt.Println(g.perim())
}
func main() {
r := rect{width: 3, height: 4}
c := circle{radius: 5}
measure(r) // run measure against rect
measure(c) // run measure against circle
}