forked from steger/pr3-ws202526
67 lines
1.1 KiB
Go
67 lines
1.1 KiB
Go
package main
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import (
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"fmt"
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"math"
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)
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type geometry interface {
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area() float64
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perim() float64
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}
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type rect struct {
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width, height float64
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}
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// Ensure that rect implements the geometry interface
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var _ geometry = rect{}
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type circle struct {
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radius float64
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}
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// Ensure that circle implements the geometry interface
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var _ geometry = circle{}
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func (r rect) area() float64 {
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return r.width * r.height
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}
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func (r rect) perim() float64 {
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return 2*r.width + 2*r.height
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}
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func (c circle) area() float64 {
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return math.Pi * c.radius * c.radius
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}
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func (c circle) perim() float64 {
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return 2 * math.Pi * c.radius
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}
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//Metods demonstrates how to use an interface
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func measure(g geometry) {
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fmt.Println(g)
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fmt.Println(g.area())
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fmt.Println(g.perim())
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}
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//Method demonstrates casting an interface to a concrete type.
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//Should be avoided in practice whenever possible.
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func detectCircle(g geometry) {
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if c, ok := g.(circle); ok {
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fmt.Println("circle with radius", c.radius)
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}
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}
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func main() {
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r := rect{width: 3, height: 4}
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c := circle{radius: 5}
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measure(r)
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measure(c)
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detectCircle(r)
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detectCircle(c)
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}
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