Hi, I'm playing with `explicit backing fields` ``...

# getting-started

[ursus]

Hi, I'm playing with explicit backing fields

interface VersionChecker {
    val supportedVersion: Flow<Boolean>
}

class VersionCheckerImpl(
    ...
) : VersionChecker {
    override val supportedVersion: Flow<Boolean>
        field = MutableStateFlow(true)

    ...
}

and this fails to compile with Properties with explicit backing fields must be final.
Which granted is true, but - is really this the desired outcome? In a production app, it's most likely that this will be the pattern (exposed via interface), rendering the feature kinda useless

[Šimon Kručinin]

The production version is more like:

private val mutableSupportedVersion = MutableStateFlow(true)
override val supportedVersion: Flow<Boolean>
  get() = mutableSupportedVersion

Or you can assign directly and hope no one re-types it at runtime:

override val supportedVersion: Flow<Boolean> = MutableStateFlow(true)

field is useful for local transformation during assignment or validation, but there are other ways, too. This is probably the easiest though.

[ursus]

Hm? Explicit backing fields is a new syntactic sugar for syntax you spelled out

[Šimon Kručinin]

Sorry, my bad. I misunderstood your original post.

[Šimon Kručinin]

Anyway, you can mark your property in VersionCheckerImpl as final override, can’t you?
In many cases, you don’t need to extend the implementation class further, just to implement the interface. The feature would still be useful in these scenarios.

[ursus]

I mean the class is final so that cant happen but ill try