interrupting REPL ILoop programmatically

Question

i have a wrapper for the scala REPL api (ILoop etc...) using the refactored 2.9.x classes.

this works well.

as this is a tool shipped to users, it is possible the user will type something like :

while(-1 < 1) {}

how can the user break from the currentlly executing code?

other posts talk about

<ctrl> + <c> 

kind of working on some platforms under appropriate key bindings.

inspecting the scala REPL api and any available docs, it isnt obious how to actually implement this.

Answer 1

Check out how the Scala REPL does it in the file ILoopInit.scala. There the following signal interrupt handler is installed,

  protected def installSigIntHandler() {
    // ....
    SignalManager("INT") = {
      if (intp == null || intp.lineManager == null)
        onExit()
      else if (intp.lineManager.running)
        intp.lineManager.cancel()
      // ...
    }
  }

Note that the field intp: IMain is defined in class ILoop, which is the self-type of ILoopInit.

To summarize: in your SIGINT handler you can interrupt the REPL with intp.lineManager.cancel.