在使用过程中，如何为没有任何参数的类型创建构造函数

Question

Given this type

type Response map[string]interface{}

I created a method NewResponse which fills in the default values:

 func NewResponse() Response {
    resp := Response{"status": 200, "msg": "Added jobs to queue"}

    resp_metadata := make(map[string]string)
    resp_metadata["base"] = "api/v1"
    resp_metadata["self"] = "/crawler/jobs/add"
    resp["metadata"] = resp_metadata
    return resp
}

which i call like NewResponse() but I would like to do Response.New() instead, so the method signature should be like this

func (Response) New() Response {

but then I always get the error not enough arguments in call to Response.New.

So, how could this be implemented?

Answer 1

Although it is definitely not idiomatic Go, you could do something like this:

type Response map[string]interface{}

func (r *Response) New() {
  *r = make(map[string]interface{})
  (*r)["hello"] = "World"
  (*r)["high"] = 5
}

func main() {
  var r Response
  r.New()
  for k, v := range r {
    fmt.Printf("%s = %v
", k, v)
  }
}

But really, there's nothing wrong with func NewResponse() Response.