Does anyone know if there is a place to submit feature requests for ktx. I have been thinking about ...

# android

[540grunkspin]

Does anyone know if there is a place to submit feature requests for ktx. I have been thinking about Parcel.readSparseArray. It returns SparseArray without any generic parameter and I am not aware of a way to read it with the generic parameter. It should be fairly easy to reify that one to do a cast for you. I know that this is not something that is super hard to do yourself but it feels like a hack every time i need to suppress the unchecked cast warning.

[gildor]

Report it here
https://issuetracker.google.com/issues/new?component=396204

[gildor]

but it feels like a hack every time i need to suppress the unchecked cast warning

You also can write extension function to encapsulate this behavior

[540grunkspin]

Yeah sure I can. I was thinking that the goal of ktx was to reduce boilerplate and this is something that I find myself doing in nearly every project

[gildor]

Yeah, sure, you may report

[gildor]

A problem that this function is always unsafe and this cast actually do not check items type, so your code may crash in some unexpected place trying to use this collection

[gildor]

For sure such function also may validate items, but probably it’s overkill for most use cases

[540grunkspin]

Yeah maybe slap on an @Trows annotation. Or return a SparseArray?

[gildor]

No, you didn’t get what I mean

[gildor]

also @Throws is useless, this annotation make sense only for Java interop

[540grunkspin]

True. But do you mean that the code can succeed the cast but crash when accessing the items?

[gildor]

see:

val input = SparseArray<Any>()
input.put(0, "String!") // Put string
a.writeSparseArray(input)
val output = a.readSparseArray(javaClass.classLoader) as SparseArray<Int> // No exception here!
val item: Int = output.get(0) // Exception will happen here!

[gildor]

if you extract a.readSparseArray(javaClass.classLoader) as SparseArray<Int> to function this function will return successfully, but cast will fail

[540grunkspin]

Oh this was news to me but I guess it make sense since type erasure.

[gildor]

Yes

[540grunkspin]

Yeah then maybe I will just have to continue adding an extension and name it something like readUncheckedSparseArray

[gildor]

You can try to write something like that:

inline fun <reified T> Parcel.readAndCastSparseArray(): SparseArray<T>? {
    val sparseArray = readSparseArray(javaClass.classLoader) ?: return null
    for (index in 0 until sparseArray.size()) {
        val value = sparseArray.valueAt(index)
        if (value != null && value !is T) {
            throw ClassCastException("Value $value on index $index cast failed to ${T::class}")
        }
    }
    @Suppress("UNCHECKED_CAST")
    return sparseArray as SparseArray<T>
}

[gildor]

CAREFUL, NOT TESTED

[gildor]

just an idea

[540grunkspin]

Looks cool! Will for sure give it a try!