Add KPlatform & KDefaultPlatform

[buenaflor]

I came across two issues in this PR:

Issue 1

findLoggingClass uses Class which is not easily typealiased in commonMain because Class and KClass have different signatures:

• public class Class
• public interface KClass

My solution here is to create an expect class Klass<T: Any> which will typealias directly to Class on JVM and on iOS it will save the KClass reference in a variable.

• JVM: public actual typealias Klass<T> = Class<T>
• iOS: public actual class Klass<T : Any>(public val kClass: KClass<T>)

Additionally KClass will have an extension function: public expect fun <T : Any> KClass<T>.toKlass()

The usage looks like this in commonMain

KPlatform.getCallerFinder().findLoggingClass(MyClass::class.toKlass())

Note: I couldn't come up with a better name other than Klass but I'm pretty sure there is a much better name for this

Why this solution

It's important to be able to use actual typealias on the JVM side so I opted for keeping the Class signature even though it's never going to be used directly as you can only create a Klass through the toKlass() method through KClass in the common code.

Issue 2

If the findLoggingClass is called from a companion object in Kotlin the StackFrame classname will include an extra $Companion - this doesn't work in the default Java implementation because this case is not accounted for (probably because the codebase is written only in Java) and will throw an IllegalStateException because it cannot find the correct StackFrame.

Example:

Kotlin: com.example.test.FluentLogger$Companion
Java: com.example.test.FluentLogger

Solution:

// KFlogger: To handle Kotlin companion calls we need to check for names suffixed with $Companion
return f -> f.getClassName().equals(name) || f.getClassName().equals(name + "$Companion");

However this solution requires a small change in the Flogger codebase.

@MarkCMann

[buenaflor]

Small change in the Java Flogger codebase

[buenaflor]

Klass workaround to make actual typealias work with Platform

[MarkCMann]

Looks good, reflection is one of the rough edges for KMP

[MarkCMann]

Looks good, reflection is one of the rough edges for KMP

[MarkCMann]

Do you want to define some properties, functions, or extension functions here? It's unclear what benefits you get by making this class an expected class -- although it looks like the usages are opaque to callers outside KFlogger so maybe this is okay.

[buenaflor]

Usages won't be really a concern outside of KFlogger, the reason why it's an expected class is because it typealiases directly on JVM to Class and on iOS it saves the reference to the KClass. It's basically a "bridge" class without functionality just so we can keep the Java typealias. In it's current state it's only used in findLoggingClass