If I have a base class with few hundred fields (basically constants, but not declared as static) wil...

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[Karlo Lozovina]

If I have a base class with few hundred fields (basically constants, but not declared as static) will the derived classes also have hundreds of fields in memory? or will the JVM somehow optimize that?

[diesieben07]

Fields are inherited. So if you make an instance of the subclass it will still have space for the fields. After all, someone could still use the fields.

[Karlo Lozovina]

thanks! so for space saving I guess static fields are the way to go

[diesieben07]

Constants should be in an object regardless, yes

[streetsofboston]

@Karlo Lozovina I’m curious what your use-case is…

[streetsofboston]

Is it just about constants, like

class MyClass {
    val CONST_1 = 3
}

vs

class MyClass {
    companion object {
        val CONST_1 = 3
    }
}

[Karlo Lozovina]

@streetsofboston nothing too interesting, some code generation going on, trying to go lower on memory usage...

[Karlo Lozovina]

it would be nice if static fields could be required as part of interfaces...

[diesieben07]

Kotlin does not have "static" for this very reason. Make an interface for those fields and implement that interface on the companion object.

[streetsofboston]

You could make a plain object or a companion object implement an `interface`…

[Karlo Lozovina]

huh, that could maybe work... I'd have to split things into multiple classes but still...

[Karlo Lozovina]

thanks for the idea