Composition visibility

Language Design
1

I suppose, internal visibility is rarely used in projects because it’s wide and packages are shuffled often. But what could be useful is a visibility scope to be seen only between children and parents or composition variables. Like

class Foo() {
    internal_private fun invisibleOutside() {}
}

class Bar(foo: Foo) {
    init {
        foo.invisibleOutside()
    }
}

And it’s good to be available in interfaces as well.

2

What do you mean by “children and parents or composition variables”? When exactly should it be visible?

Visibility modifiers is a looong story in Kotlin :slight_smile: BTW, I personally use internal quite a lot.

3

If you’re using modules then internal should be pretty common.
The Gradle docs do a decent job of pointing in the right direction for structuring projects: Structuring Large Projects
^ The next few pages on that link talk about best practices, etc.

4

As I remember, custom visibility scope can be created, but I don’t remember if Java supports it.
Something like only close family can use it, between internal and protected. Maybe the visibility inside of a single package could be enough.