Re: [Caml-list] [OSR] OCaml Standard Recommandation Process

[Christophe TROESTLER <Christophe.Troestler+ocaml@umh.ac.be>]

On Mon, 28 Jan 2008 17:20:16 +0100, Nicolas Pouillard wrote:
> 
> Excerpts from christophe.troestler+ocaml's message of Mon Jan 28 17:06:10 +0100 2008:
> > On Mon, 28 Jan 2008 15:25:12 +0000, Jon Harrop wrote:
> > > 
> > > So you write a "use" binding:
> > > 
> > >   let read_first_line file =
> > >     use ch = open_in file in
> > >     input_line ch
> > > 
> > > and it gets translated into:
> > > 
> > >   let read_first_line file =
> > >     let ch = open_in file in
> > >     try input_line ch finally
> > >     ch#dispose
> > > 
> > > where the "dispose" method that was automatically inserted at
> > > the end of the scope of the "use" binding calls "close_in" in
> > > this case to deallocate the external resource (a file handle in
> > > this case but it could be anything with a dispose method).
> > 
> > What is wrong with
> > 
> >    let read_first_line file =
> >      with_open_in file begin fun ch ->
> >        input_line ch
> >      end
> 
> This  code  has  nothing  wrong but with_open_in (even if it's very useful) is
> not resource safe. This is because the in_channel can escape it's scope.
> 
> | let ch = with_open_in file (fun x -> x) in
> | input_line ch
> 
> This program is obviously wrong but still show that with_open_in is not safe.

Right but how is it different with "use" ?

ChriS