Arg.spec and option types

Arg.spec and option types

[Nicolas barnier]

Hi list,

I find the recent addition of the Set_{string|int|float} constructors
of type Arg.spec quite useful, as it spares a lot of repeated code
for processing command line arguments. However, for optional arguments,
I often feel the need (and write the code) to handle option types,
which can elegantly be processed to trigger optional behaviours of a
program.

I think it would therefore be quite useful to add 
Set_option_{string|int|float}
constructors which would expect {string|int|float} option ref values as
arguments (usually initialized with None). Do others think the same or use
some other workaround to obtain this behaviour ?

-- Nicolas

Re: Arg.spec and option types

[Sam Steingold]

Nicolas barnier wrote:
> 
> I think it would therefore be quite useful to add 
> Set_option_{string|int|float}
> constructors which would expect {string|int|float} option ref values as
> arguments (usually initialized with None). Do others think the same or use
> some other workaround to obtain this behaviour ?

It is nice to know that I am not the only one who is writing
  Arg.String (fun s -> foo := Some s)
all the time.

Sam.

Re: [Caml-list] Re: Arg.spec and option types

[Nicolas Pouillard]

On 3/22/07, Sam Steingold <sds@gnu.org> wrote:
> Nicolas barnier wrote:
> >
> > I think it would therefore be quite useful to add
> > Set_option_{string|int|float}
> > constructors which would expect {string|int|float} option ref values as
> > arguments (usually initialized with None). Do others think the same or use
> > some other workaround to obtain this behaviour ?
>
> It is nice to know that I am not the only one who is writing
>   Arg.String (fun s -> foo := Some s)
> all the time.
>
> Sam.
>

What about,

let opt_str r = Arg.String (fun s -> r := Some s);;

... opt_str foo ...

That's what I use all the time.

-- 
Nicolas Pouillard