CODEWITHSUNDEEP
scala
Alain
Alain

Reputation: 971

How can a private field be accessed from another object instance?

I'm currently looking how covariant and contravariant type parametrization is handled in Scala. And there's a special case, where a var field must be private[this] in order to compile. From example in this code snippet (taken in this question: private[this] vs private):

class Holder[+T] (initialValue: Option[T]) {
    // without [this] it will not compile
    private[this] var value = initialValue

    def getValue = value
    def makeEmpty { value = None }
}

I understand this example. But what I can't understand, is in what case is a private field accessible from another instance than itselt (this)?

Thanks for your help.

Upvotes: 2

Views: 508

Answers (1)

David Harkness
David Harkness

Reputation: 36522

If a member is plain-private, it is accessible from other instances of the same class. The [this] suffix makes it visible only to the instance that contains it.

Upvotes: 5

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