Kotlin protected property can not be accessed in other module-CodePudding

Just when I thought I understood it, I got the following issue.

I have a base class in another module (called base here)

It looks like that:

open class BaseTest {
    companion object {
        lateinit var baseTest: BaseTest
    }
    protected open var someProperty: String? = "base"
}

I want to set that property and made it protected so my extended class in another module could access it.

class Extended: BaseTest() {

    fun extendedCall() {
        BaseTest().someProperty = "extended"
        baseTest.someProperty = "extended"
    }
}

However, neither the static one, not the direct property is accessable stating the following error:

Cannot access 'someProperty': it is protected in 'BaseTest'

But shouldn't that be accessable since Extended inherents from BaseTest()? I mean the definition of protected is "Declarations are only visible in its class and in its subclassess" so what have I missed? It even doesn't work in the same module so that's not the cause.

What am I missing?

CodePudding user response：

    BaseTest().someProperty = "extended"

Here you make a new BaseTest object by calling the constructor BaseTest() and you are not allowed to access protected properties of other BaseTest objects.

    baseTest.someProperty = "extended"

the static BaseTest object is also another object and not the Extended object itself.

Being protected merely makes it possible to do

    someProperty = "extended"

or the equivalent

    this.someProperty = "extended"

That is, access the property of this object.

CodePudding user response：

I believe the protected modifier doesn't work like that in Kotlin.

The documentation says:

The protected modifier is not available for top-level declarations.

But I agree it's quite confusing as written. It appears the documentation focuses more on the Outter/Inner class relationship via the this keyword.