Hmhm struggling to find a good name for a extension function kotlinlang #codereview

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Title

d

Daniel

03/25/2020, 10:15 PM

Hmhm, struggling to find a good name for a extension function that returns true when two lists have identical content (same references).

fun <T> List<T>.isSameAs(other: List<T>): Boolean {
        if(size != other.size) return false

        forEachIndexed { index, element ->
            if(element !== other[index]) return false
        }

        return true
    }

Does anybody have an idea? Also maybe there might be a better way to check this?

s

Shawn

03/25/2020, 10:31 PM

I think that’s about as good as you can get it really - assuming order matters and

hashCode()

isn’t good enough for equality. You might consider adding an

if (this === other) return true

but it’s not strictly necessary

also maybe just call it

identicalTo()

as a personal point of style I don’t really like

forEach/forEachIndexed

for side-effect-ey operations that aren’t at the end of a call chain but that’s a nit more than anything in this case

b

bitnot

03/26/2020, 9:55 AM

is it different from

contentEquals

? https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/content-equals.html

m

Mike

03/26/2020, 12:33 PM

contentEquals

is for Array, not List. Otherwise, I think they're the same, and you have just provided a meaningful name.

s

Shawn

03/26/2020, 2:55 PM

contentEquals

compares with `==

.equals()`, the requirement was identity equality of the elements

===

I think this is about as concise as I could get it

infix fun <E> List<E>.identicalTo(other: List<E>): Boolean = when {
  this === other -> true
  size != other.size -> false
  else -> withIndex().all { (index, value) ->
    value === other[index]
  }
}

or this very mildly cursed looking thing

infix fun <E> List<E>.identicalTo(other: List<E>): Boolean =
    other === this
        || other.size == size
        && withIndex().all { (index, value) ->
      value == other[index]
    }

d

Daniel

03/26/2020, 5:58 PM

Thank you all! Curious usecase and understandable, that this isn't in the standard lib

👍 1

The withIndex is smart!

🙏 1

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