✨ New ClassIdentity type

[LVMVRQUXL]

📝 Description

We want to introduce a ClassIdentity experimental type, in the org.kotools.types package of the types Gradle subproject, for representing the identity of a class.

This type should have the following Application Programming Interface (API)

/** Represents a class identity of type [T]. */
interface ClassIdentity<T : Any> {
    /** The name of the class. */
    val name: String

    /** The package containing the class. */
    val packageName: String

    /** Returns the string representation of this class identity. */
    override fun toString(): String

    /** Contains static declarations for the [ClassIdentity] type. */
    companion object {
        /** Creates an instance of [ClassIdentity] for the type [T]. */
        inline fun <reified T : Any> of(): ClassIdentity<T> = TODO()
    }
}

The of factory function being inlined, these declarations should be inaccessible for Java sources.

✅ Checklist

• ✨ Add the type with documentation and dump the Application Binary Interface (ABI).
• ✨ Add the of() function with documentation, tests, samples and dump the ABI.
• ✨ Add the name property with documentation, tests, samples, and dump the ABI.
• ✨ Add the packageName property with documentation, tests, samples, and dump the ABI.
• ✨ Override the toString() function with documentation, tests, samples, and dump the ABI.
• 📝 Add an entry for this issue in the unreleased changelog.

[LVMVRQUXL]

We need more time to think about how can we get the package of a class in a Kotlin Multiplatform project.

[LVMVRQUXL]

A solution is to provide different implementations of this type for each platform.

On the JVM and Native platforms, calling the toString() function should return the qualified name of the corresponding type.

val identity = ClassIdentity.of<Int>()
println(identity) // kotlin.Int

On the JS platform, calling the same function should return the simple name of the corresponding type.

val identity = ClassIdentity.of<Int>()
println(identity) // Int

---

EDIT on 2024-04-19: This solution is valuable only for serialization, but not for identifying the class in a Java class system. The problem is that, on Kotlin/JS platform, a first.A type and another second.A type would be considered the same regarding this strategy of using the simple name.

A better solution would be to provide the package name to the of factory function, and checking on the Kotlin/JVM and the Kotlin Native platforms that the result of calling the ClassIdentity.toString() function should always return the qualified name of the specified class.

val zeroIdentity: ClassIdentity<Zero> = ClassIdentity.of<Zero>(within = "org.kotools.types")
val actual: String = zeroIdentity.toString()
val expected: String? = Zero::class.qualifiedName
println(actual == expected) // true

[LVMVRQUXL]

The name and the packageName properties shouldn't be exposed as String but as NotBlankString at least.