How to modify a setting in a command and retain other session changes?

Question

I have this simple command that changes the value of myBoolSetting:

commands += Command("mycommand") {
    state ⇒ (Space ~> Bool).?
} { (state, arg) ⇒
    val b = arg.getOrElse(true)
    Project.extract(state).append(Seq(myBoolSetting in Global := b), state)
}

When I change invoke it does change myBoolSetting but I lose any setting whose value has been changed by means of the set command.

> set myStringSetting := "new value"
> myCommand false

In this example, the value of myStringSetting has been lost and has its default value.

How can I change a setting and keep manual changed settings?

UPDATE:

Found related question: Why sbt.Extracted remove the previously defined TaskKey while append method?, but seems not to work in my case.

Modified code:

commands += Command("mycommand") {
    state ⇒ (Space ~> Bool).?
} { (state, arg) ⇒
    val b = arg.getOrElse(true)
    val session = Project.session(state)
    val state2 = Project.extract(state).append(Seq(myBoolSetting in Global := b), state)
    SessionSettings.reapply(session, state2)
}

score 1 · Answer 1 · answered Dec 18 '15 at 02:04

1

I might only partially answer your question.

The reason for losing myStringSetting new value is that myCommand reloads a session effectively leaving you with what you have already in build.sbt-like files and what the command itself set. You simply drop the value while reloading the session.

It is similar to doing set scalaVersion := "2.11.7" and reload afterwards. scalaVersion becomes the default Scala version you had in sbt configuration.

You now know why you lose the value. If you want to retain the value you'd have to save the current session session save and execute your command. You need to add session save to your command.

answered Dec 18 '15 at 02:04

Jacek Laskowski

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This answer is partial but provides a clue. Thanks. – david.perez Dec 18 '15 at 08:28
Glad it helped a bit. Why don't you simply `session save` before calling a command? It's by design that as the session gets dropped all the temporary values will, too. – Jacek Laskowski Dec 18 '15 at 19:10
My objective is to incrementally change the session settings. – david.perez Dec 21 '15 at 11:44
In addition `session save` does change my `build.sbt`, and it can cause git conflicts. – david.perez Dec 21 '15 at 11:50
Ah, so you want to retain temporary session changes without saving them? – Jacek Laskowski Dec 21 '15 at 17:36
Yes, just changing session state. – david.perez Dec 22 '15 at 08:33

How to modify a setting in a command and retain other session changes?

1 Answers1