I mean I really likes the smart casts, this feels ...

# getting-started

[ursus]

I mean I really likes the smart casts, this feels like a step back

[Shawn]

the point of smart casting isn’t to be lazy, it’s to be safe

[ursus]

whats the issue? that it doesnt know its kotlin in the other module?

[Shawn]

even if it were Kotlin in the foreign code, it could have a computed getter

[ursus]

how come it works on the same module code then

[Shawn]

it won’t work in the same module if it has a computed getter

[ursus]

I see

[ursus]

can contracts or whatever help in future?

[Shawn]

no, consider the following, valid and representable computed getter

[Shawn]

Screen Shot 2020-04-08 at 11.34.46 PM.png

[ursus]

yea computed getter I get, I mean real vals

[Shawn]

here it is in text form if the screenshot is hard to read

class Foo {
  val bar: Int?
    get() = if (Random.nextInt() % 2 == 0) 4 else null
}

fun bar(foo: Foo) {
    if (foo.bar != null) {
        acceptsInt(foo.bar)
    }
}

[ursus]

constant dataclass vals, from another module, can I nudge compiler somehow to accept it?

[ursus]

if its "my" code

[Shawn]

you gotta draw the line somewhere, and the line was drawn at modules

[Shawn]

Maybe in the future the JB folks will come up with a way to safely relax those requirements, but for the time being those are the rules, and they’re there to keep us from shooting our feet off

[ursus]

I understand, but, wondering if its a setting or a maybe some metaprogramming of contracts etc

[ursus]

on the typeinference

[Shawn]

this problem is out of the scope of the type system though

[Shawn]

and contracts can’t really guarantee the safety of external code

[ursus]

I mean it did work until recently I think, I thought it was the new type inference engine

[ursus]

unless im wrong

[Shawn]

in the three years I’ve been writing Kotlin, I’ve never seen this work

[Shawn]

maybe a long time ago before 1.0 this could’ve been the case but I have no idea

[ursus]

really? nevermind then, thanks

[Shawn]

https://discuss.kotlinlang.org/t/what-is-the-reason-behind-smart-cast-being-impossible-to-perform-when-referenced-class-is-in-another-module/2201/2

[David Eriksson]

https://kotlinlang.slack.com/archives/C0922A726/p1586327104061700

[Kroppeb]

this kinda what I do most of the time

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