Go语言应用闭包之返回函数

func Add2() (func(b int) int)
func Adder(a int) (func(b int) int)

package main
import "fmt"
func main() {
	// make an Add2 function, give it a name p2, and call it:
	p2 := Add2()
	fmt.Printf("Call Add2 for 3 gives: %v\n", p2(3))
	// make a special Adder function, a gets value 2:
	TwoAdder := Adder(2)
	fmt.Printf("The result is: %v\n", TwoAdder(3))
}
func Add2() func(b int) int {
	return func(b int) int {
		return b + 2
	}
}
func Adder(a int) func(b int) int {
	return func(b int) int {
		return a + b
	}
}

package main
import "fmt"
func main() {
	var f = Adder()
	fmt.Print(f(1), " - ")
	fmt.Print(f(20), " - ")
	fmt.Print(f(300))
}
func Adder() func(int) int {
	var x int
	return func(delta int) int {
		x += delta
		return x
	}
}

var g int
go func(i int) {
	s := 0
	for j := 0; j < i; j++ { s += j }
	g = s
}(1000) // Passes argument 1000 to the function literal.

func MakeAddSuffix(suffix string) func(string) string {
	return func(name string) string {
		if !strings.HasSuffix(name, suffix) {
			return name + suffix
		}
		return name
	}
}

addBmp := MakeAddSuffix(".bmp")
addJpeg := MakeAddSuffix(".jpeg")

addBmp("file") // returns: file.bmp
addJpeg("file") // returns: file.jpeg