Hello! Is there a way to extend `State` . I want t...

# javascript

[Nikolai Sviridov]

Hello! Is there a way to extend State . I want to create function which changes state in different Component classes.

// external interface as example, but it will not work
external interface StateWithError: State {
  var error: Throwable?
}

fun <S : StateWithError> Component<*, S>.someFunction(){
  setState { 
    error = Throwable("Some msg")
  }
}

I tried to use external interface and abstract class (even with @JsName("error") ), but always getting name mangling. Is there a way to create such function?

[Grégory Lureau]

Did you try with another name than error ? I'm thinking it could be a reserved word.

[turansky]

IR?

[Nikolai Sviridov]

@Grégory Lureau no, it doesn't work.

[Nikolai Sviridov]

@turansky yes

[turansky]

Could you check it in legacy?

[Nikolai Sviridov]

In legacy it throws Cannot read properties of undefined (reading 'pass') which likely related to another problem

[Nikolai Sviridov]

without calling the function

[turansky]

Time for function components 🙂

[Nikolai Sviridov]

Came up with this solution. In this case it can work with mutable fields of data class.

data class WrapError(var error: Throwable?)

interface StateWithError: State {
  var wrapError: WrapError
}

inline fun <S: StateWithError> Component<*, S>.setError(wrapError: WrapError) {
  setState {
    wrapError.error = Throwable("Say hello to my little friend")
  }
}