golang 函数的特殊用法

1.可以复用一些写法。经常在单元测试过程中需要new一些对象可以new的操作抽离出来

package main

import "fmt"

type S struct {
}

func (s *S) Service1(name string) {
	fmt.Println("Service 1", name)
}

func (s *S) Service2(name string) {
	fmt.Println("Service 2", name)
}

func (s *S) Service3(name string) {
	fmt.Println("Service 3", name)
}

func newService() *S {
	return &S{}
}

func withService(fn func(s *S)) func() {
	return func() {
		fn(newService())
	}
}

func main() {
	withService(func(s *S) {
		s.Service1("first")
	})()
	withService(func(s *S) {
		s.Service2("second")
	})()
	withService(func(s *S) {
		s.Service3("third")
	})()
}

2.中间件

package main

import (
	"fmt"
	"time"
)

func work(name string) {
	fmt.Println("hello ", name)
	time.Sleep(time.Second)
}

func calTime(f func(name string)) func(string) {
	t := time.Now()
	return func(n string) {
		defer func() {
			fmt.Println("time spend is ", time.Since(t))
		}()
		f(n)
	}
}

func main() {
	s := calTime(work)
	s("world")
}