annoying problem (maybe actually solved with jvm's...

# codereview

[groostav]

annoying problem (maybe actually solved with jvm's loosening of constructor rules in valhalla?):

I want to create an exception instance. I already have its stack trace as a variable, so I want to create this exception, and then set its stack trace. I want to create a custom exception type for this purpose.

What is the most idiomatic way to do this?

class MyCustomException(val trace: List<StackTraceElement>): Exception(){
    init {
        stackTrace = trace.toTypedArray()
    }

    override fun fillInStackTrace() = this //interrupt call to dump back-trace into stack-trace
}

?

[John Smith]

use setStackTrace() ? https://docs.oracle.com/javase/8/docs/api/java/lang/Throwable.html#setStackTrace-java.lang.StackTraceElement:A-

[groostav]

which simply lets the jvm spend the time of dumping the backtrace to the stack trace?

[groostav]

seems inelegant, I would think that with the stack trace in hand I could implement fillInStackTrace myself

[John Smith]

true, not very elegant

[hho]

But does it matter? Shouldn't exceptions be … you know … exceptional? So rare, that their performance never is an issue?