GoLang，“ hash.Write”，“ write（）”函数从何而来？

Question

func hash(s string) uint32 {
    h := fnv.New32a()
    h.Write([]byte(s))
    return h.Sum32()
}

For this code piece. I understand what type is h. It is hash. But for Hash type, I didn't see any Write() method. http://golang.org/pkg/hash/ what is this Write()?

thanks

Answer 1

The Hash interface embeds the Writer interface. Therefore, any type that wants to implement the Hash interface, also needs to implement the Writer interface containing the Write method.

The reason for the Write Method is that you can calculate hashes of anything that can be written. For example, you can calculate the hash of the formatted representation of an object (by using the fmt package), or you can calculate the hash of the json representation (by using the json package), etc.

h := fnv.New32a()
fmt.Fprint(h, myobject)
// alternatively:
// json.NewEncoder(h).Encode(myobject)
// etc.
return h.Sum32()