一文带你感受Go语言空结构体的魔力

var e sruct{}

type EmptyStruct struct{}
var e EmptyStruct

package main

import (
   "fmt"
   "unsafe"
)

func main() {
   var a int
   var b string
   var e struct{}
   fmt.Println(unsafe.Sizeof(a)) // 4
   fmt.Println(unsafe.Sizeof(b)) // 8
   fmt.Println(unsafe.Sizeof(e)) // 0
}

package main

import (
   "fmt"
)

func main() {
   var e struct{}
   var e2 struct{}
   fmt.Printf("%p\n", &e)  // 0x90b418
   fmt.Printf("%p\n", &e2) // 0x90b418
   fmt.Println(&e == &e2)    // true
}

// base address for all 0-byte allocations
var zerobase uintptr
func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer {
    ······
    if size == 0 {
       return unsafe.Pointer(&zerobase)
    }
    ······

package main
import"fmt"
type Set[K comparable] map[K]struct{}
func (s Set[K]) Add(val K) {
   s[val] = struct{}{}
}
func (s Set[K]) Remove(val K) {
   delete(s, val)
}
func (s Set[K]) Contains(val K) bool {
   _, ok := s[val]
   return ok
}
func main() {
   set := Set[string]{}
   set.Add("陈明勇")
   fmt.Println(set.Contains("陈明勇")) // true
   set.Remove("陈明勇")
   fmt.Println(set.Contains("陈明勇")) // false
}

package main  
import (  
   "fmt"
   "time"
)  
func main() {  
   quit := make(chanstruct{})  
   gofunc() {  
      // 模拟工作  
      fmt.Println("工作中...")  
      time.Sleep(3 * time.Second)  
      // 关闭退出信号  
      close(quit)
   }()  
   // 阻塞，等待退出信号被关闭  
   <-quit  
   fmt.Println("已收到退出信号，退出中...")  
}

type Context interface {
    Deadline() (deadline time.Time, ok bool)
    Done() <-chanstruct{}
    Err() error
    Value(key any) any
}

type Person interface {
   SayHello()
   Sleep()
}
type CMY struct{}
func (c CMY) SayHello() {
   fmt.Println("你好，我叫陈明勇。")
}
func (c CMY) Sleep() {
   fmt.Println("陈明勇睡觉中...")
}