Pavel Kunyavskiy
56 lines
1.3 KiB
Markdown
56 lines
1.3 KiB
Markdown
# Overriding with inline function
|
|
|
|
While inline function can't be open, it can override function from superclass.
|
|
|
|
```kotlin
|
|
// lib
|
|
interface I {
|
|
fun foo()
|
|
}
|
|
|
|
class A : I {
|
|
override inline fun foo() {
|
|
println("lib.v1") // changed to lib.v2 in v2
|
|
}
|
|
}
|
|
|
|
// depends on lib.v1
|
|
|
|
fun test(x: A) {
|
|
x.foo() // print("lib.v1") as it is inlined
|
|
(x as A).foo() // println("lib.v2") as it can't be inlined
|
|
}
|
|
|
|
// main depends on lib.v2
|
|
fun main() {
|
|
test(A())
|
|
}
|
|
```
|
|
|
|
This leads to inconsistency on which version would be called in which cases.
|
|
This code already emits a warning (or error if there is reified type paramter),
|
|
so we are fine with this behaviour.
|
|
|
|
On the other side, there is a trickier case with the same effect, which doesn't emit any warnings.
|
|
Probably, it is a bug, and this should be deprecated ([KT-63928](https://youtrack.jetbrains.com/issue/KT-63928)).
|
|
|
|
```kotlin
|
|
interface Foo {
|
|
fun <T> foo()
|
|
}
|
|
|
|
open class Bar {
|
|
inline fun <reified T> foo() {
|
|
println(typeOf<T>())
|
|
}
|
|
}
|
|
|
|
class Bas: Foo, Bar()
|
|
|
|
fun main() {
|
|
Bas().foo<String>() // runtime crash
|
|
}
|
|
```
|
|
|
|
This leads to a restriction: inline functions should persist as normal ones after inlining, if they can be called.
|
|
And probably, ones, that can't be called should still exist with throw exception as body. |