i'm trying to parse an environment variable with a...

# getting-started

[Richard Cumberland]

i'm trying to parse an environment variable with a sensible default, and since this is a learning experiment as much as anything else, i'd like to use pattern matching. is this is a sensible approach, or should i stick to assigning the value of a try/catch?

val port: Int = when (val p = System.getenv().getOrDefault("PORT","8080").toInt()) {
      is Int -> p
      else -> 8080
    }

[diesieben07]

Except that this won't work. toInt will throw if it can't parse it so you will just get an uncaught exception. You can only catch exceptions using try-catch. If you want to use "pattern matching", you have to use toIntOrNull, which will return null in case of an unparseable value:
val port = System.getenv().getOrDefault("PORT", "8080").toIntOrNull() ?: 8080

[Richard Cumberland]

ahaaa, thank you very much. i was wondering if the else case would catch an exception, and i guess it doesn't!

[Richard Cumberland]

is there a way to remove the val p = part of that and still use the value?

[Richard Cumberland]

declaring an intermediate value seems redundant

[diesieben07]

No, that's what the val p = syntax is for

[diesieben07]

but using when here is way overkill anyways.

[Richard Cumberland]

is there a better or more concise approach? i'm all ears 🙂

[Richard Cumberland]

or, er, all eyes

[diesieben07]

Read above 🙂

[diesieben07]

I posted an example

[Richard Cumberland]

oh so you did, my bad

[Richard Cumberland]

thank you very much dude, you rock 😄

[sitepodmatt]

there no point parsing 8080 string to int unncessarily

[sitepodmatt]

val port = System.getenv("PORT")?.toIntOrNull() ?: 8080