Object orientation in Go - Struct/Composition/ Encapsulation

Question

I have two .go files - client.go ( contains the main fund) and logic.go. One of them contains the function which needs to be executed when it is invoked from the client. {

client.go -

package main

func main() {
  // url is the url of the server to which the REST call has to be sent to fetch the response
  client := NewClient(url)
  client.DummyFunc()

}

logic.go

import (
"fmt"
)

func DummyFunc(){

   // Logic here which returns the json response
}

}

I am trying to understand what could be a good object oriented way in Go to do this. Since Go has its own style of object inheritance/composition/encapsulation, could you please suggest me a way to do this as I am new to this language.

Also, I want the main function in my client.go and logic.go should contain other utility functions which can be invoked from my client.go file.

Answer 1

Before addressing the OO way of doing this, does client.go need to hold the main function? Does logic.go need to be separated from client.go? Also, logic.go must be part of a package. I'm having a hard time picking up what was left out for brevity versus what may be missing.

How I would do things:

main.go (would be the same for both cases)

package main

import "client"

func main() {
    client := client.Client { ClientUrl: url } // This takes the place of NewClient(url)
    client.DummyFunc()
}

client.go

package client

type Client struct {
    ClientUrl      string
}

func (c Client) DummyFunc() {
    // Logic here which returns the JSON response
}

If you would like to keep logic separate from client, you could do this.

client.go

package client

type Client struct {
    ClientUrl      string
    Logic          // An anonymous field let's you call Logic functions 
}

logic.go

package client

type Logic struct {
    // Fields
}

func (l Logic) DummyFunc() {
    // Logic here which returns the JSON response
}

Notice, since we kept Logic anonymous in the Client struct, we were able to call DummyFunc.

You can see some more examples here: http://golangtutorials.blogspot.com/2011/06/inheritance-and-subclassing-in-go-or.html

EDIT --------------------------------------------------------

It's a little awkward, but here's client.go with main function in it and logic.go is separate. If you add more functions in logic, then client will be able to call all other functions.

client.go

package main

import "logic"

type Client struct {
    ClientUrl      string
    logic.Logic
}

func main() {
    client := client.Client { ClientUrl: url } // This takes the place of NewClient(url)
    client.DummyFunc()
}

logic.go

package logic

import "fmt"

type Logic struct {
    // Fields
}

func (l Logic) DummyFunc() {
    fmt.Printf("In DummyFunc\n")
}

With that being said, I'm not sure this is the best way to do it. If logic doesn't have any fields, then it makes no sense to have it as a separate struct. I would make it a function of client, as I pointed out in the first case in the original post.