Kotlin: calling outer class method in object expression

Question

My question is almost like this question Java: calling outer class method in anonymous inner class . But this time we are in Kotlin.

As the example below, I want to call funB() in the object expression, but I only made two failures.

class A { lateinit var funA: () -> Unit lateinit var funB: () -> Unit fun funC() { var b = object : B() { override fun funB() { funA() // A.funA() // Two attempts to fail funB() // b.funB(), not my expect A::funB() // compile error } } } }

Thank you for your answer!

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yole
– yole

2018-07-30 09:52:15 +00:00
Commented Jul 30, 2018 at 9:52 — yole
– yole, Commented Jul 30, 2018 at 9:52
@yole that's an answer ;)

user2340612
– user2340612

2018-07-30 10:07:27 +00:00
Commented Jul 30, 2018 at 10:07 — user2340612
– user2340612, Commented Jul 30, 2018 at 10:07

crgarridos · Accepted Answer · 2018-07-30 10:03:30Z

You can qualify this with a @ to obtain an equivalent of java: MyClass.this ->this@MyClass

Then in your case, you can call:

[email protected]()

From the doc:

To access this from an outer scope (a class, or extension function, or labeled function literal with receiver) we write this@label where @label is a label on the scope this is meant to be from:

class A { // implicit label @A inner class B { // implicit label @B fun Int.foo() { // implicit label @foo val a = this@A // A's this val b = this@B // B's this val c = this // foo()'s receiver, an Int val c1 = this@foo // foo()'s receiver, an Int val funLit = lambda@ fun String.() { val d = this // funLit's receiver } val funLit2 = { s: String -> // foo()'s receiver, since enclosing lambda expression // doesn't have any receiver val d1 = this } } } }

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