well. `null` is not supported with protobuf. that ...

# serialization

[thana]

well. null is not supported with protobuf. that is a HUGE drawback

[sandwwraith]

Protobuf originally does not have concept of null, only presence and absence of value which is hard to map unambiguously on Kotlin's default values/default nullable values/nullable values without default/...

[thana]

yes found the bug report for this problem. i''l have a look what i can do 🙂

[thana]

is it only the nullable types with default values that cause the problems? or default values themselves?

[sandwwraith]

There are several problems there. What you should deserialize into val x: Int? = 42 if x is missing? Even non-nullable val x: Int = 42 can cause problems because protobuf specs clearly says that "absence of value should be treated as 0 for primitives and - huh - 'field is not set. Its exact value is language-dependent' for non-primitive types".

[sandwwraith]

Java's protobuf implementation uses null as 'not set', but we can't afford such luxury in Kotlin

[thana]

well i guess there are more problems here? at least those to seem to be easily solvable at first glane 🤔

[thana]

in the first case i'd guess if x is missing it was explicitly set to null in the second case the serialized form would simply missmatch

[thana]

what i couldn't fin out yet: is there anything i can do?