52 lines
1012 B
Go
52 lines
1012 B
Go
// staticchecking/petspeak.go
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// (c)2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
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package main
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import "fmt"
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type Cat struct {}
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func (this Cat) speak() { fmt.Printf("meow!\n")}
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type Dog struct {}
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func (this Dog) speak() { fmt.Printf("woof!\n")}
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type Bob struct {}
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func (this Bob) bow() {
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fmt.Printf("thank you, thank you!\n")
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}
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func (this Bob) speak() {
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fmt.Printf("Welcome to the neighborhood!\n")
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}
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func (this Bob) drive() {
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fmt.Printf("beep, beep!\n")
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}
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type Speaker interface {
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speak()
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}
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func command(s Speaker) { s.speak() }
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// If "Speaker" is never used
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// anywhere else, it can be anonymous:
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func command2(s interface { speak() }) { s.speak() }
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func main() {
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command(Cat{})
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command(Dog{})
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command(Bob{})
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command2(Cat{})
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command2(Dog{})
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command2(Bob{})
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}
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/* Output:
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meow!
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woof!
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Welcome to the neighborhood!
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meow!
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woof!
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Welcome to the neighborhood!
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*/
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