56 lines
1.0 KiB
Go
56 lines
1.0 KiB
Go
// Interfaces are named collections of method signatures
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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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// basic interface for geometric shapes
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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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// implement interface on rect and circle types
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type rect struct {
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width, height float64
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}
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type circle struct {
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radius float64
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}
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// implement geometry on rects
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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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// implementation for circles
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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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// call methods that are in the named 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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func main() {
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r := rect{width: 3, height: 4}
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c := circle{radius: 5}
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// circle and rect struct types both implement the geometry interface
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// use instances of these structs as arguments to measure
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measure(r)
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measure(c)
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}
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