Scala Scope
Examples
Public (default) scope
By default, the scope is public, the value can be accessed from anywhere.
package com.example {
class FooClass {
val x = "foo"
}
}
package an.other.package {
class BarClass {
val foo = new com.example.FooClass
foo.x // <- Accessing a public value from another package
}
}A private scope
When the scope is private, it can only be accessed from the current class or other instances of the current class.
package com.example {
class FooClass {
private val x = "foo"
def aFoo(otherFoo: FooClass) {
otherFoo.x // <- Accessing from another instance of the same class
}
}
class BarClass {
val f = new FooClass
f.x // <- This will not compile
}
}A private package-specific scope
You can specify a package where the private value can be accessed.
package com.example {
class FooClass {
private val x = "foo"
private[example] val y = "bar"
}
class BarClass {
val f = new FooClass
f.x // <- Will not compile
f.y // <- Will compile
}
}Object private scope
The most restrictive scope is "object-private" scope, which only allows that value to be accessed from the same instance of the object.
class FooClass {
private[this] val x = "foo"
def aFoo(otherFoo: FooClass) = {
otherFoo.x // <- This will not compile, accessing x outside the object instance
}
}Protected scope
The protected scope allows the value to be accessed from any subclasses of the current class.
class FooClass {
protected val x = "foo"
}
class BarClass extends FooClass {
val y = x // It is a subclass instance, will compile
}
class ClassB {
val f = new FooClass
f.x // <- This will not compile
}