How to construct nested structs with slices

Question

I am building a simple group manager in which I share with you the relevant part only. I am having a trouble with understanding how the things work in Object-like structs without constructors (and copy constructors in particular).

main.go

var currentGroup Headers.Group

func main() {

    currentGroup.New(0)

    p := Headers.Process{ID: uint16(len(currentGroup.Processes)), Address: "Test"}
    currentGroup.AddProcess(p)
    p.PrintProcess()
    currentGroup.PrintGroup()
}

I have a class-like called Process

Process.go

//Process defines a Process structure
type Process struct {
    ID      uint16
    Address string
}

type processFuncs interface {
    printProcess()
}

//PrintProcess prints a process contents
func (p Process) PrintProcess() {

    fmt.Printf("[P%d; %s]\n", p.ID, p.Address)
}

and a group class-like

Group.go

// Group struct
type Group struct {
    ID        uint16
    Processes []Process
}

//AddProcess adds a process to the group
func (G Group) AddProcess(p Process) {

    G.Processes = append(G.Processes, p)
}

//PrintGroup prints the group processes
func (G Group) PrintGroup() {

    fmt.Printf("=========================\nGroup %d:\n", G.ID)
    for i := 0; i < len(G.Processes); i++ {
        G.Processes[i].PrintProcess()
    }
}

//New Group Constructor
func (G Group) New(ID uint16) {
    G.ID = ID
    G.Processes = make([]Process, 0)
}

Screen Output:

[P0; Test]
=========================
Group 0:

Expected Screen Output:

[P0; Test]
=========================
Group 0:
[P0; Test]

Problem: The Process p is created and printed successfully, but not added to currentGroup .

Question: What I know is that slice append function copies by value. Then, a Process object/struct is copied without the need of creating a slice of pointers. Hence the process struct is considered as an indivisible object. Is that true? Any misunderstanding? Anything wrong with the code?

Answer 1

Here I'll drop some hints for you. Which are mostly my learning when i started using golang. Please match not only the syntax but also the casing.

type processFuncs interface {
    **printProcess**()
}

//PrintProcess prints a process contents
func (p Process) **PrintProcess**() {

    fmt.Printf("[P%d; %s]\n", p.ID, p.Address)
}

another important point: functions, methods or variables/members starting with Capital letter are exported (same as Public), starting in small case un-exported(more like private or better package level access).

You usually expose your interfaces and make the actual types unexported. Add a new method to create the type object.

Second if you want to modify the type object with the method call use pointer reference instead of value ie

Use func (p *Process) PrintProcess(){
//... do something
}

instead of

func (p Process) PrintProcess(){
//... do something
}

Most importantly Go is not like Java or C# or any other OO language so don't write OO code in golang.