golang 类/type

  
//类定义
  
type Mutex struct {
        
state int32
        
sema uint32
    
}

//扩展已定义类型
   
type Num int32
      
func (num Num) IsBigger(otherNum Num) bool {
          
return num > otherNum
      
}

//类方法
  
type Once struct {
      
m Mutex
      
done uint32
  
}

func (o *Once) Do(f func()) {
      
if atomic.LoadUint32(&o.done) == 1 {
          
return
      
}
      
// Slow-path.
      
o.m.Lock()
      
defer o.m.Unlock()
      
if o.done == 0 {
          
defer atomic.StoreUint32(&o.done, 1)
          
f()
      
}
  
}