CLI - Scallop

[leobenkel]

Put Scallop specific code in its own component and make the default version more generic

[DamianReeves]

I can take a look at this.

[leobenkel]

i would recommend doing those:

1. create a dummy project using today's set up
2. test --help
3. look at the log which described the used commands
4. access arguments from the application using the snippet of code below (the object Arguments)
5. test passing a wrong command line
6. try to access it in

   ZparkIO/Library/src/main/scala/com/leobenkel/zparkio/Services/SparkModule.scala

   Line 31 in 95de593

   arguments: C

   to add a spark.option(...)
7. then, try removing scallop from build.sbt and from

   ZparkIO/Library/src/main/scala/com/leobenkel/zparkio/Services/CommandLineArguments.scala

   Line 18 in 95de593

   trait Service extends ScallopConf {

8. replace what breaks by un-implmented methods in the trait
9. create a new module with scallop to cut and paste the previous implementation into this isolated module
10. go back to your dummy project and add the zparkio library as well as the zparkio-scallop library. it should work the same way
11. copy your dummy project and try to make it work with an other config library.

How to use CommandLine today:

class Arguments(override val args: Seq[String])
    extends ScallopConf(args) with CommandLineArguments.Service {
...
}

object Arguments {
  type ArgumentEnv = CommandLineArguments.CommandLineArguments[Arguments]

  def apply(): ZIO[ArgumentEnv, Throwable, Arguments] =
    CommandLineArguments.apply[Arguments]()

  def apply[A](f: Arguments => A): ZIO[ArgumentEnv, Throwable, A] =
    CommandLineArguments.get[Arguments].map(_.apply(f))
}

which allow to do :

for {
   path <- Arguments(_.readPath)
   ds <- readUserFrom(path)
} yield ds