threading a question asking about Find Usages (or alternatives) for a function `typealias` or functi...

# intellij

[Ted Naleid]

threading a question asking about Find Usages (or alternatives) for a function typealias or function signature

[Ted Naleid]

Our code uses typealias for a function signature fairly heavily. Here is small made-up example:

data class Widget(val name: String)
typealias PersistWidget = (Widget) -> Boolean

class RealBackend {
    // other functions, not something that can be just a SAM
    fun persist(widget: Widget): Boolean = TODO()
}

class FakeBackend {
    fun persistSuccess(widget: Widget): Boolean = true
    fun persistFailure(widget: Widget): Boolean = false
}

class Facade(val persist: PersistWidget) {
    fun createWidget(): Widget {
        val widget = Widget("default")
        return if (persist(widget)) {
            widget
        } else {
            throw Exception("failed to persist")
        }
    }
}

fun main() {
    val backend = FakeBackend()
    val facade = Facade(backend::persistSuccess)
    facade.createWidget()
}

[Ted Naleid]

If PersistWidget were an interface, it'd be easy to find all of the classes that implement that interface

[Ted Naleid]

but with a typealias I'm not aware of an equivalent ability to find all things that have the same type signature as my typealias

[Ted Naleid]

is there some way of using Find Usages, or similar, to find all of the things in my code that have the same type signature as the PersistWidget typealias?

[Ted Naleid]

right now, I can cmd-B on the PersistWidget and it'll show me that there is a single use of it in this line:

class Facade(val persist: PersistWidget) {

which is correct for explicit usages of that

[Ted Naleid]

but I'd also like it to be able to expand that search so that it also shows me functions that are effectively that typealias as well, so that it'd show me these too:

[Ted Naleid]

I found a sort of similar question in history that seems to imply that it's possible but I haven't figured out how: https://kotlinlang.slack.com/archives/C0B8H786P/p1585584873009600

[Alexey Belkov [JB]]

I think it's not possible. Can you please create a feature request at http://kotl.in/issue and describe your use case with sample code attached? Thanks!

[Ted Naleid]

Will do, thanks!

[Ted Naleid]

created: https://youtrack.jetbrains.com/issue/IDEA-258194