Env vars are not bound when `CoreCliktCommand` is used

[JakeWharton]

CliktCommand works fine. CoreSuspendingCliktCommand also broken.

Works:

fun main(vararg args: String) {
	ExampleCommand().main(args)
}

private const val envVarName = "THIS_IS_A_TEST"

private class ExampleCommand : CliktCommand() {
	private val value by option(envvar = envVarName)

	override fun run() {
		println("env: " + System.getenv(envVarName))
		println("property: $value")
	}
}

❯ gw -q installDist && THIS_IS_A_TEST=hello ./build/install/clikt-env-vars/bin/clikt-env-vars
env: hello
property: hello

Does not work:

fun main(vararg args: String) {
	ExampleCommand().main(args)
}

private const val envVarName = "THIS_IS_A_TEST"

private class ExampleCommand : CoreCliktCommand() {
	private val value by option(envvar = envVarName)

	override fun run() {
		println("env: " + System.getenv(envVarName))
		println("property: $value")
	}
}

❯ gw -q installDist && THIS_IS_A_TEST=hello ./build/install/clikt-env-vars/bin/clikt-env-vars
env: hello
property: null

[JakeWharton]

Okay so this is documented: https://ajalt.github.io/clikt/advanced/#core-module

However, it seems like Mordant really should not be required for most of these things. Reading env vars in a multiplatform context is a few lines. Reading files is more lines, but not a ridiculous amount of lines. In that list, the only thing that screams Mordant to me is "Text wrapping, formatting, markdown, or color support".

Can we work to move the others into having core support?

[JakeWharton]

@ajalt Are you open to this? I'm happy to work on it. I just got hit by it once again.

[ajalt]

Right now CliktCore doesn't have any target specific code, so it can easily compile to every target. I'm a little hesitant to add this for that reason.

[JakeWharton]

What about throwing an exception if you specify an envvar binding in a CoreCliktCommand without a envvar provider specified?

[ajalt]

That's a good idea. Have you ran into this with the automatic envvar name assignment, or is it enough to throw if you explicitly set an envvar name?

[JakeWharton]

Oh, I didn't know there was an automatic one. It's only bit me when I set them explicitly for use in a Docker container.

[oharaandrew314]

For JVM, I managed to work around this with a small inclusion to my main command. I chose not to use the clikt jvm module because I'm optimizing for minimal footprint; mordant and JNA were unnecessary.

class SystemCli: CoreCliktCommand("system") {
    init {
        context {
            readEnvvar = System::getenv // jvm-only
        }
    }

    override fun run() = Unit
}