Nullable properties or extensions for well known wrappers

[aszorenyi]

The library supports well known wrappers (Int32Value, StringValue etc.), the generated constructors has generated nullable wrapper variables (IntValue?, StringValue? etc.) but the properties are not null (paired with isSet properties).

Is it possible to have either generated nullable properties with the respective primitive (Int?, String? etc.) or to have generated extension properties (propertyNameOrNull) like with the default kotlinDSL proto gen?

[TimOrtel]

Currently, this is not possible. The reason for this lies in the definition of the protobuf language, where default values should be returned even when no explicit value is set. You can read up on this topic here: https://protobuf.dev/programming-guides/proto3/#default

[aszorenyi]

I suspected that the reason is similar, but I think some additional (or extension) properties can exist.

Let's say I have a field named A which is a StringValue. At the moment the generated class will have a field named A as a non-nullable StringValue and an isASet boolean property. We can generate a property (or an extension in a separate file) AOrNull where it would look like this:
val AOrNull: StringValue? get() = if (isASet) A else null

This pattern can be used for all non-primitve properties, not just wrappers, io.grpc protoc-gen-kotlin is doing something similar (for JVM).

But of course it is acceptable if you don't want to do something like this in this library, this was just an idea. :)

[TimOrtel]

Your proposal sounds quite useful. I'd probably add them as extension functions/properties.

I think it makes sense to add them to the project. Do you think you can provide a PR for this? Otherwise I'd try to do it when I find the time.

[aszorenyi]

Unfortunately I'm working overtime on a project using the library. I will try to create a PR when I can find some time (at the moment I'm using the isSet functions).