Access variable name in lambda function

Question

I'm trying to access the name of a variable inside an iterator

listOf(someClassVariable, anotherClassVariable, yetAnotherClassVariable).forEach {
    if (it.foo()) {
        map.add(it, ::it.name)
    }
}

but getting unsupported [references to variables aren't supported yet] error at ::it.name. Any ideas/workarounds?

do you just want to return the value of it.name? or do you actually want something like a supplier or similar that will return the name, when you access the supplier? (something like a lazy evaluation?) — Roland
– Roland, Commented Feb 20, 2019 at 16:24
Hi @Roland I want the name of the variable, not a property called "name". So for the first case it would be map.add(someClassVariable, "someClassVariable") — fhomovc
– fhomovc, Commented Feb 20, 2019 at 16:29
ah ok... now I got you... interesting... this doesn't seem to work yet, even though ::someClassVariable.name would... what are you trying to accomplish that way? maybe there is another approach too... I mean: now you manually put all the variables into the list... if that becomes more dynamic maybe also the rest will solve itself more easily? ;-) — Roland
– Roland, Commented Feb 20, 2019 at 16:37

Roland · Accepted Answer · 2019-02-20 16:49:58Z

3

You could do it vice-versa, i.e. having a list of references to your class variables and iterate over them and then get the actual value by calling invoke on it:

listOf(::someClassVariable, ::anotherClassVariable, ::yetAnotherClassVariable).forEach { varRef ->
    val varValue = varRef() // assignment optional... you can also just do it the way you want ;-)
    if (varValue.foo())
        map.add(varValue, varRef.name)
}

answered Feb 20, 2019 at 16:49

Roland

23.5k5 gold badges62 silver badges91 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

fhomovc Over a year ago

Nice approach ;-) Thanks!

Collectives™ on Stack Overflow

Access variable name in lambda function

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related