Golang: struct inside an interface?

Question

So I have an interface, called UserService inside a package service

I have two simple structs representing the body and response of a HTTP call. I have another struct implementing the UserService interface.

I want to put these structs, call them UserResponse and UserRequest inside the interface so other services can use them to make the HTTP call. Furthermore, the request and response should be available (struct UserReponse, not struct userResponse) so other parts of the code can use them.

I define a function in the interface called GetUser(request UserRequest) UserResponse

However, whenever I reference UserRequest I have to use service.UserRequest and not service.UserService.UserRequest. This is bad because I don't want user-related objects to go into the service namespace. I want each service related data to organized under its own interface, file, etc. Unfortunately, I get an error if I put UserResponse inside the UserService interface. So I put it at the same level as UserService, which is why they are showing up as service.UserResponse. How do I go about accessing UserResponse as service.UserService.UserResponse?

You don't. Interfaces only define a method set. If you demonstrate what problem you're trying to solve with actual code, we may be better able to help. — Mr_Pink
– Mr_Pink, Commented Aug 12, 2015 at 13:47
why not just move model objects into their own package? sounds to me like it's a code structure problem and not interface/struct related. Just open a package called model and have everyone reference it. — Not_a_Golfer
– Not_a_Golfer, Commented Aug 12, 2015 at 14:07

kostya · Accepted Answer · 2015-08-12 14:22:36Z

Here is a suggestion to organize your code in more "idiomatic" Go way:

package user

type Request struct {
    ...
}

type Response struct {
    ...
}

type Service interface {
   GetUser(r Request) Response
}

Outside of user package the code will look like:

s := user.NewService()
var req user.Request
var resp user.Response
resp = s.GetUser(req)

As you can see the code uses much shorter names and still remains very readable.

Package names like service shows that you organize the code in your app by layers instead of by features. I wouldn't recommend it. Here is interesting article about it: http://www.javapractices.com/topic/TopicAction.do?Id=205. It uses Java but the principle applies to any programming language.

Yup, it dawned on me after asking the question that I should make a new folder (package) and put user related code in there. Now I have a user/data.go and user/service.go and it should work.

Etienne Membrives · Accepted Answer · 2015-08-12 14:08:12Z

-1

Go is not Java; Go is even not C++. You should think of Go as "C with interfaces".

In particular, you cannot do as you want, as you cannot nest struct definitions in interface definitions. Note that you can nest structs inside structs, but you cannot instantiate a nested struct directly.

The closest you can do is to move each logical group of objects to its own package.

answered Aug 12, 2015 at 14:08

Etienne Membrives

8791 gold badge8 silver badges13 bronze badges

Collectives™ on Stack Overflow

Golang: struct inside an interface?

2 Answers 2

1 Comment

Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Related