Please remind me about the following: If I declare...

# announcements

[hallvard]

Please remind me about the following: If I declare a Long in my class, say var f: Long = 5, and in the course of my program, the value changes. And then I would like this check: if (f == 10000) { ... }. Why is it that it doesn't compile? Why do I need to supply an L to the hard-coded constant 10000 here? Shouldn't it be possible for the compiler to detect that 10000 is valid as a Long value?

[Shawn]

It might be within range as a Long value, but it’ll still fail .equals(). I don’t know enough about numeric types on the JVM to really explain why, but I think this is an instance of the compiler disallowing a comparison to avoid subtle bugs

[Shawn]

in the repl I tried a simple 5L.equals(5) which evaluated to false

[Shawn]

I think there’s only a single Long.equals(Any?) defined, so it makes sense that the method would include a other is Long check

[Shawn]

== is supposed to resolve to an equals() call in Kotlin, but it wouldn’t be useful here and perhaps harmful to the developer to allow it. If implicit widening were allowed, you’d have Int values autoconverted to Long that suddenly wouldn’t be able to be compared to ints and it wouldn’t be obvious from the code why

[hallvard]

Thanks.

[ilya.gorbunov]

It's a known issue, please vote for/follow the discussion in https://youtrack.jetbrains.com/issue/KT-3936