Re: [Caml-list] Using common arguments with Command module of the Core library

[Ben Millwood <bmillwood@janestreet.com>]

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There are a few ways of doing this. The newly-added Applicative interface
is worth showing off:

let shared_params =
  let open Command.Param in
  return (fun v c rcfile ->
    verb := v;
    color := c;
    rcfile)
    <*> flag "-v" (optional_with_default 0 int) ~doc:"..."
    <*> flag "-c" (...) ~doc:"..."
    <*> ...

shared_params is now a package of arguments that sets the verb and color
refs and then gives you the rcfile (it's only that way to mirror your code;
I'd usually prefer to just put all three in a record or something). You can
use it in Command.basic as follows:

let sum =
  Command.basic
    ~summary:"whatever"
    Command.Spec.(
      empty
      +> shared_params
      +> anon ...)
      (fun rc ... () -> ...)

let main () =
  Command.run begin
    Command.group ~summary:"some stuff"
      [ "sum", sum
      ; "settings", ...
      ]
  end

Let me know if I've omitted too much :)

On 3 August 2015 at 13:18, <leowzukw@vmail.me> wrote:

> Hello everybody,
>
> I'm trying to use subcommands with the Core library. I would like to
> factorize several things :
>
>    - A set of common arguments (to set color, verbosity and so on)
>    - A common way to deal with these arguments
>    - A pretty way to define subcommands using these common arguments and
>    way to handle it.
>
>
>
> Main problem is that I can't define more arguments to my subcommand. More
> details in my code, which is joined. You may also find it here (Github
> gist, could be updated): http://j.mp/1JHlZ6S
>
>
>
> Result of the compilation (corebuild cmd.byte)
>
>
> + ocamlfind ocamlc -c -w A-4-33-40-41-42-43-34-44 -strict-sequence -g
> -bin-annot -short-paths -thread -syntax camlp4o -package bin_prot.syntax
> -package
> sexplib.syntax,comparelib.syntax,fieldslib.syntax,variantslib.syntax
> -package core -o cmd.cmo cmd.ml
> File "cmd.ml", line 98, characters 5-44:
> Warning 48: implicit elimination of optional argument ?extend
> File "cmd.ml", line 49, characters 11-341:
> Warning 27: unused variable summary.
> File "cmd.ml", line 49, characters 20-341:
> Warning 27: unused variable args.
> Finished, 3 targets (0 cached) in 00:00:03.
>
>
> Thanks for your help
> Leo
>
>

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