Use Arg module to read keyword followed by unspecified number of arguments

Use Arg module to read keyword followed by unspecified number of arguments

[mulhern]

Hi!

I expect to be reading something like this:

-pred-files <arg1> <arg2> ... <argn> -key2 <arg> -extra-files <arg1>
<arg2> ... <argn> -key4

There may be 0 or more <args> specified after -pred-files and after
-extra-files. I need to treat the args differently depending on what
keyword they are associated with.

I can think of about 10 ways to do this using the Arg module, but
they're all ugly and all different. Does anybody have an attractive
solution to this problem or is aware of the accepted way to handle
this situation? An example in some existing code would be good enough.

I do not consider changing the call to
-pred-files <arg1> -pred-files <arg2> ... -pred-files <argn> ......
an option at this time, principally because the call is automatically
generated and I'ld like it to stay in line with the other
automatically generated calls in the same distribution.

Thanks!

-mulhern

Re: [Caml-list] Use Arg module to read keyword followed by unspecified number of arguments

[Till Varoquaux]

You could work around with references but I guess you'd consider this
as ugly. A comma separated list of strings could do the trick:
 "-pred-files", Arg.String (fun s -> predfiles:=Str.split
(Str.regexp_string ",") s),"...")

cheers,
Till
On 5/23/06, mulhern <mulhern@gmail.com> wrote:
> Hi!
>
> I expect to be reading something like this:
>
> -pred-files <arg1> <arg2> ... <argn> -key2 <arg> -extra-files <arg1>
> <arg2> ... <argn> -key4
>
> There may be 0 or more <args> specified after -pred-files and after
> -extra-files. I need to treat the args differently depending on what
> keyword they are associated with.
>
> I can think of about 10 ways to do this using the Arg module, but
> they're all ugly and all different. Does anybody have an attractive
> solution to this problem or is aware of the accepted way to handle
> this situation? An example in some existing code would be good enough.
>
> I do not consider changing the call to
> -pred-files <arg1> -pred-files <arg2> ... -pred-files <argn> ......
> an option at this time, principally because the call is automatically
> generated and I'ld like it to stay in line with the other
> automatically generated calls in the same distribution.
>
> Thanks!
>
> -mulhern
>
> _______________________________________________
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> Archives: http://caml.inria.fr
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> Bug reports: http://caml.inria.fr/bin/caml-bugs
>

Re: [Caml-list] Use Arg module to read keyword followed by unspecified number of arguments

[Oliver Bandel]

On Tue, May 23, 2006 at 12:17:18PM -0500, mulhern wrote:
> Hi!
> 
> I expect to be reading something like this:
> 
> -pred-files <arg1> <arg2> ... <argn> -key2 <arg> -extra-files <arg1>
> <arg2> ... <argn> -key4
> 
> There may be 0 or more <args> specified after -pred-files and after
> -extra-files. I need to treat the args differently depending on what
> keyword they are associated with.

Do you need a keyword for these pred-files arg's?

Why don't you use un-named (anonyme) args?

It looks like a filelist.

The last anonymous function ( "(fun name -> if Sy.file_exists name"(...) )
will be called for all args that are givewn, without a switch that
specifies which kind of arg will follow.


Example:

let parse () = (*print_endline "OK, starting the parse!";*)
    Arg.parse [
         ("-dp", Arg.String (fun x -> dirnameopt := Prefix x), " <dirpref> directory name-prefix");
         ("-fd", Arg.String (fun x -> dirnameopt := Fixed x), "<fixdir> fixed directory name");
         ("-inv", Arg.Unit (fun () -> filter_selection := Inverted ), " invert the template filter ... <template>" );
         ("-ad", Arg.Unit (fun () -> fk_sel := Allow_dirs ), " allow dirs to be moved ...!" );
         ("-v", Arg.Unit (fun () -> Printf.printf "%s\n" version;exit 0), " version of the program" )
              ] 
         ( fun name -> if Sys.file_exists name then Hashtbl.replace filenames name "" ) 
         "Use the program with following options:"




Hope, this helps.



Ciao,
   Oliver

Re: [Caml-list] Use Arg module to read keyword followed by unspecified number of arguments

[Oliver Bandel]

On Tue, May 23, 2006 at 12:17:18PM -0500, mulhern wrote:
> Hi!
> 
> I expect to be reading something like this:
> 
> -pred-files <arg1> <arg2> ... <argn> -key2 <arg> -extra-files <arg1>
> <arg2> ... <argn> -key4
> 
> There may be 0 or more <args> specified after -pred-files and after
> -extra-files. I need to treat the args differently depending on what
> keyword they are associated with.

You could maybe change what args you want to have.
If one arglist with arbitrary number of args would be sufficient,
you could do it with anonymous args, as I stated in my last mail.

If this does not work, you maybe should parse Sys.argv by your own.

Ciao,
   Oliver

Re: [Caml-list] Use Arg module to read keyword followed by unspecified number of arguments

[Michael Wohlwend]

On Tuesday 23 May 2006 19:17, mulhern wrote:
> Hi!
>
> I expect to be reading something like this:
>
> -pred-files <arg1> <arg2> ... <argn> -key2 <arg> -extra-files <arg1>
> <arg2> ... <argn> -key4

I think the idea by Till to separate the args with commas is best, but if you 
don't want to do this, maybe something like that would be o.k. :

let mode_pred = ref true;;
let pred_files = ref [];;
let extra_files = ref [];;
let key2 = ref "";;

Arg.parse [
	"-extra-files", Arg.Clear mode_pred, "extra files";
	"-key2", Arg.Set_string key2, "key2";
	"-pred-files", Arg.Set mode_pred, "pred files"
	]
	(fun name -> if !mode_pred then
		 	pred_files := name :: !pred_files
		else
			extra_files := name :: !extra_files
	) "usage..."
;;


cheers,
 Michael


-- 
C offers you enough rope to hang yourself.
C++ offers a fully equipped firing squad, a last cigarette and
a blindfold.

Re: [Caml-list] Use Arg module to read keyword followed by unspecified number of arguments

[Till Varoquaux]

Actualy I'd stick with double references... (yuck). From the top of my head:
let a=ref [];;
let b=ref [];;
let c=ref a;;

let p_list l=
        List.iter (Printf.printf "\"%s\"") l;
        print_newline ()

let _=
        Arg.parse [("-switch",Arg.Unit (fun () -> c:=b),"")]
                (fun s -> !c:=s::!(!c))
                "blah";
        p_list !a;
        p_list !b

Note how c is a double reference...

Till

On 5/23/06, Michael Wohlwend <micha-1@fantasymail.de> wrote:
> On Tuesday 23 May 2006 19:17, mulhern wrote:
> > Hi!
> >
> > I expect to be reading something like this:
> >
> > -pred-files <arg1> <arg2> ... <argn> -key2 <arg> -extra-files <arg1>
> > <arg2> ... <argn> -key4
>
> I think the idea by Till to separate the args with commas is best, but if you
> don't want to do this, maybe something like that would be o.k. :
>
> let mode_pred = ref true;;
> let pred_files = ref [];;
> let extra_files = ref [];;
> let key2 = ref "";;
>
> Arg.parse [
>         "-extra-files", Arg.Clear mode_pred, "extra files";
>         "-key2", Arg.Set_string key2, "key2";
>         "-pred-files", Arg.Set mode_pred, "pred files"
>         ]
>         (fun name -> if !mode_pred then
>                         pred_files := name :: !pred_files
>                 else
>                         extra_files := name :: !extra_files
>         ) "usage..."
> ;;
>
>
> cheers,
>  Michael
>
>
> --
> C offers you enough rope to hang yourself.
> C++ offers a fully equipped firing squad, a last cigarette and
> a blindfold.
>
> _______________________________________________
> Caml-list mailing list. Subscription management:
> http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list
> Archives: http://caml.inria.fr
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>

Re: [Caml-list] Use Arg module to read keyword followed by unspecified number of arguments

[Michael Wohlwend]

On Tuesday 23 May 2006 21:50, Till Varoquaux wrote:
> Actualy I'd stick with double references... (yuck). From the top of my

I like that  :-)

 Michael


--
C offers you enough rope to hang yourself.
C++ offers a fully equipped firing squad, a last cigarette and
a blindfold.

Re: [Caml-list] Use Arg module to read keyword followed by unspecified number of arguments

[Richard Jones]

On Tue, May 23, 2006 at 12:17:18PM -0500, mulhern wrote:
> Hi!
> 
> I expect to be reading something like this:
> 
> -pred-files <arg1> <arg2> ... <argn> -key2 <arg> -extra-files <arg1>
> <arg2> ... <argn> -key4

Have you thought about _not_ using the Arg module?  A loop with
pattern matching is often good enough, or in this case two nested
loops:

let pred_files = ref []
let key2 = ref ""
let extra_files = ref []
let key4 = ref ""

let rec read_args = function
  | "-pred-files" :: args ->
      let args, rest = read_to_next_switch args in
      pred_files := args;
      read_args rest
  | "-key2" :: arg :: rest ->
      key2 := arg;
      read_args rest
  | "-extra-files" :: args ->
      let args, rest = read_to_next_switch args in
      extra_files := args;
      read_args rest
  | "-key4" :: arg :: rest ->
      key4 := arg;
      read_args rest
  | [] -> ()
  | arg :: _ ->
      prerr_endline (arg ^ ": unknown parameter");
      exit 2

and read_to_next_switch = function
  | (switch :: _) as rest when String.length switch > 0 && switch.[0] = '-' ->
      [], rest
  | arg :: rest ->
      let args, rest = read_to_next_switch rest in
      arg :: args, rest
  | [] ->
      [], []
  ;;

read_args (List.tl (Array.to_list Sys.argv)) ;;

print_endline ("pred-files = " ^ String.concat ", " !pred_files) ;;
print_endline ("key2 = " ^ !key2) ;;
print_endline ("extra-files = " ^ String.concat ", " !extra_files) ;;
print_endline ("key4 = " ^ !key4) ;;

----------------------------------------------------------------------
$ ./parse -pred-files arg1 arg2 arg3 -key2 key2 -extra-files arg1 arg2 -key4 key4
pred-files = arg1, arg2, arg3
key2 = key2
extra-files = arg1, arg2
key4 = key4

Rich.

-- 
Richard Jones, CTO Merjis Ltd.
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