Re: [Caml-list] Format question

[Gerd Stolpmann <info@gerd-stolpmann.de>]

Am 2002.11.07 01:09 schrieb(en) Oleg:
> Oleg wrote: 
> 
> >
> > Is it possible to define a printf that automatically flushes stdout?
> >
> 
> I figured it out:
> 
> let my_printf (x : ('a, out_channel, unit) format) = 
>    let tmp = Printf.printf x in flush stdout; tmp;;

No that does not work, output is flushed before anything is printed,
at least if the format string requires an argument. E.g.

# my_printf "%d" 6; prerr_endline "a";;
a
6- : unit = ()

(prerr_endline implies flushing stderr.) In this example, tmp has
type int->unit, and the 6 is applied to tmp after flushing has
been done.

You need kprintf:

let my_printf = Printf.kprintf (fun s -> print_string s; flush stdout; s);;

Unfortunately, my_printf results always in a string. This can't be changed
in O'Caml 3.06, but I have recently seen that there is an improved
kprintf in CVS.

Gerd

------------------------------------------------------------
Gerd Stolpmann * Viktoriastr. 45 * 64293 Darmstadt * Germany 
gerd@gerd-stolpmann.de          http://www.gerd-stolpmann.de
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