Can functions be passed as parameters?
Here is the sample "Map" implementation in Go. Hope this helps!!
func square(num int) int {
return num * num
}
func mapper(f func(int) int, alist []int) []int {
var a = make([]int, len(alist), len(alist))
for index, val := range alist {
a[index] = f(val)
}
return a
}
func main() {
alist := []int{4, 5, 6, 7}
result := mapper(square, alist)
fmt.Println(result)
}
Here is a simple example:
package main
import "fmt"
func plusTwo() (func(v int) (int)) {
return func(v int) (int) {
return v+2
}
}
func plusX(x int) (func(v int) (int)) {
return func(v int) (int) {
return v+x
}
}
func main() {
p := plusTwo()
fmt.Printf("3+2: %d\n", p(3))
px := plusX(3)
fmt.Printf("3+3: %d\n", px(3))
}
Yes, consider some of these examples:
package main
import "fmt"
// convert types take an int and return a string value.
type convert func(int) string
// value implements convert, returning x as string.
func value(x int) string {
return fmt.Sprintf("%v", x)
}
// quote123 passes 123 to convert func and returns quoted string.
func quote123(fn convert) string {
return fmt.Sprintf("%q", fn(123))
}
func main() {
var result string
result = value(123)
fmt.Println(result)
// Output: 123
result = quote123(value)
fmt.Println(result)
// Output: "123"
result = quote123(func(x int) string { return fmt.Sprintf("%b", x) })
fmt.Println(result)
// Output: "1111011"
foo := func(x int) string { return "foo" }
result = quote123(foo)
fmt.Println(result)
// Output: "foo"
_ = convert(foo) // confirm foo satisfies convert at runtime
// fails due to argument type
// _ = convert(func(x float64) string { return "" })
}
Play: http://play.golang.org/p/XNMtrDUDS0
Tour: https://tour.golang.org/moretypes/25 (Function Closures)
You can pass function as parameter to a Go function. Here is an example of passing function as parameter to another Go function:
package main
import "fmt"
type fn func(int)
func myfn1(i int) {
fmt.Printf("\ni is %v", i)
}
func myfn2(i int) {
fmt.Printf("\ni is %v", i)
}
func test(f fn, val int) {
f(val)
}
func main() {
test(myfn1, 123)
test(myfn2, 321)
}
You can try this out at: https://play.golang.org/p/9mAOUWGp0k