Empty Struct
Usage
There are 3 typical usage of empty struct struct{}.
- Used as a place holder.
// for example, implementation of HashSet
type Set map[int]struct{}
func NewSet() Set {
return map[int]struct{}{}
}
func (s Set) Add(item int) {
s[item] = struct{}{}
}
func (s Set) Remove(item int) {
if _, ok := s[item]; ok {
delete(s, item)
}
}
- Use as signal without data
// Used to pass signal
func WorkControl() {
ch := make(chan struct{}, 1)
go func(chan struct{}) {
// do some work
fmt.Println("doing work...")
fmt.Println("doing done")
ch <- struct{}{}
}(ch)
select {
case <-ch:
fmt.Println("ok")
}
}
- Define simple interface implementations
type InterfaceImplementation struct{}
func(i *InterfaceImplementation) Method() {
}
But why should we use it like this? Mainly reason is struct{} uses NO memory space
zerobase
Before we talk about zerobase, let check this code piece first
func ExploreZerobase() {
a := struct{}{}
b := struct{}{}
fmt.Println(a == b)
fmt.Println(&a == &b)
//fmt.Println(&a, &b)
fmt.Println(&a == &b)
}