RE: [Caml-list] <DKIM> Re: Vagaries of Printf variants

[David Allsopp <dra-news@metastack.com>]

Pierre Chambart wrote:
> On 28/10/2014 10:19, Gabriel Scherer wrote:
> > If you know from the start that you need this flexibility, the easiest
> > way is probably to use Printf.bprintf from the start, which is
> > reasonably efficient and flexible (or write your fprintf-formats with
> > %s rather than %a).
> >
> > If you specifically need to convert code that uses (f)printf with
> > minimal changes, you have the problem that your %a/%t functions work
> > with out_channel, not strings. The simplest way out is probably to use
> > Unix.pipe (which is available on Windows) to create an out_channel
> > that you write into and read back the content as a string.
> I wouldn't recommend something like that: you are exposing yourself to
> deadlocks.
> If you are not carefull, your write will reach the OS-defined limit to the
> pipe size, and will block the process until someone reads the pipe. So you
> will need another thread to read the channel...

That's a good point, thanks. Though my use-case here is strictly for console output, where blowing the minimum 4K allocated to the pipe would be unlikely - however, it can be easily solved with a C thread (rather than the weight of an OCaml thread).


David