Private embedded struct when importing a struct from another package

Issue

I have a project which relies on a struct imported from another package, which I will call TheirEntity.

In the example below, I (ahem) embed TheirEntity in MyEntity, which is an extension of TheirEntity, with added functionality.

However, I don’t want to export TheirEntity in the MyEntity structure, as I would rather the consumer not access TheirEntity directly.

I know that Go embedding is not the same as inheritance in classical OOP, so maybe this is not the correct approach, but is it possible to specify embedded structs as “private”, even if they are imported from another package? How might one achieve the same thing in a more idiomatic fashion?

// TheirEntity contains functionality I would like to use...

type TheirEntity struct {
    name string
}

func (t TheirEntity) PrintName() {
    fmt.Println(t.name)
}

func NewTheirEntity(name string) *TheirEntity {
    return &TheirEntity{name: name}
}

// ... by embedding in MyEntity

type MyEntity struct {
    *TheirEntity // However, I don't want to expose 
                 // TheirEntity directly. How to embed this
                 // without exporting and not changing this
                 // to a named field?

    color        string
}

func (m MyEntity) PrintFavoriteColor() {
    fmt.Println(m.color)
}

func NewMyEntity(name string, color string) *MyEntity {
    return &MyEntity{
        TheirEntity: NewTheirEntity(name),
        color:       color,
    }
}

Solution

[I]s it possible to specify embedded structs as “private”, even if they are imported from another package?

No.

How might one achieve the same thing in a more idiomatic fashion?

By not-embedding but making it a unexported named field.

Answered By – Volker

Answer Checked By – Mildred Charles (GoLangFix Admin)

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