Feature Suggestion: exec method

[yschimke]

This method seems like a useful default to provide within the library. Covers help, shell completion hooks, error handling etc.

https://github.com/rsocket/rsocket-cli/blob/master/src/main/kotlin/io/rsocket/cli/Main.kt#L363

private fun exec(runnable: Main, args: List<String>) {
      val cmd = CommandLine(runnable)
      try {
        val parseResult = cmd.parseArgs(*args.toTypedArray())

        if (cmd.isUsageHelpRequested) {
          cmd.usage(cmd.out)
          exitProcess(parseResult.commandSpec().exitCodeOnUsageHelp())
        } else if (cmd.isVersionHelpRequested) {
          cmd.printVersionHelp(cmd.out)
          exitProcess(parseResult.commandSpec().exitCodeOnVersionHelp())
        }

        if (runnable.completionScript) {
          print(picocli.AutoComplete.bash("rsocket-cli", cmd))
        } else {
          runnable.run()
        }

        exitProcess(0)
      } catch (pe: CommandLine.ParameterException) {
        cmd.err.println(pe.message)
        if (!CommandLine.UnmatchedArgumentException.printSuggestions(pe, cmd.err)) {
          cmd.usage(cmd.err)
        }
        exitProcess(cmd.commandSpec.exitCodeOnInvalidInput())
      } catch (ue: UsageException) {
        cmd.err.println(ue.message)
        cmd.usage(cmd.err)
        exitProcess(cmd.commandSpec.exitCodeOnInvalidInput())
      } catch (ex: Exception) {
        ex.printStackTrace(cmd.err)
        exitProcess(cmd.commandSpec.exitCodeOnExecutionException())
      }
}

[yschimke]

@remkop I might start with a PR for this function. On the other random suggestions, let me know if you are keen and we can dicsuss on those issues what the APIs could look like and I'll contribute some PRs over time.

[yschimke]

Just found CommandLine.execute()

[remkop]

Oh, I see, I was looking at rsocket/rsocket-cli@099792f and wondering if there was a problem with CommandLine.execute() that you needed to work around. 😟
Mystery solved! 😄

[yschimke]

It would be useful to have some of the value adds supported without additional main entry points e.g. generating the completion file. Would make installations simpler as they could call the app on the fly. But nope, all good. Just missed it.

[yschimke]

Is it mentioned in the getting started docs? It’s a useful first approach.

[remkop]

The execute API is relatively new (previously there were run and call static methods, but these didn’t have exit code support).

I added a new section to the user manual. Maybe I should add additional pointers.
Where would be a good place? The readme?

[yschimke]

I think as the first item for any user facing docs. The minimal example should be that method and a main class runnable with a few options.

[remkop]

Makes sense. I updated the README, will also update the javadoc for CommandLine and any other place I find.