Re: call-with-input-file

["Paul T. Graunke" <ptg@ccs.neu.edu>]

Perhaps the confusion is about call-with-input-file vs with-input-from-file.
The function call-with-input-file does not "restore the old input port"
because it never changed the current-input-port to begin with.  Instead
it passes the input port as an argument.  That is

  (call-with-input-file "my-file" (lambda (in) (read)))

reads from the current-input-port (usually the keyboard) rather than
from my-file.

Paul

On Fri, Oct 19, 2001 at 10:03:31AM -0600, Matthew Flatt wrote:
> Quoting MichaelL@frogware.com:
> > This may be as intended, but in case it's not: with-input-from-file 
> > restores the old input port, but call-with-input-file doesn't. It seems 
> > like they both should. (I've looked at the source, so I understand why 
> > it's happening; I'm just asking whether or not the two really should 
> > behave differently.)
> 
> Arguably, `with-input-from-file' shouldn't restore the current input
> port on exit unless it's replacing the one put there by
> `with-input-from-file' on entry. But it currently behaves in a way
> that's consistent with `parameterize' expressions in general, so I'm
> inclined to leave it as-in.
> 
> In any case, the current behavior should be better documented.
> 
> Matthew