GNU bug report logs - #12216
peek-char incorrectly *CONSUMES* eof

Previous Next

Full log

View this message in rfc822 format

From: Mark H Weaver <mhw <at> netris.org>
To: Andy Wingo <wingo <at> pobox.com>
Cc: almkglor <almkglor <at> gmail.com>, dwheeler <at> dwheeler.com, 12216 <12216 <at> debbugs.gnu.org>
Subject: bug#12216: peek-char incorrectly *CONSUMES* eof
Date: Wed, 13 Mar 2013 14:10:15 -0400

Andy Wingo <wingo <at> pobox.com> writes:

> On Wed 13 Mar 2013 14:09, "David A. Wheeler" <dwheeler <at> dwheeler.com> writes:
>
>> Andy Wingo:
>>
>>> So, we are repeating ourselves here :)  I agree with you but I can't see
>>> a good way of implementing this.
>>
>> Would the per-port reader options be reasonable place to store the info
>> about EOF?
>
> For your own purposes that would be fine.  But it cannot affect
> read-char / peek-char / etc for everyone, because it would have bad
> global effects on performance and correctness.  That's why I'm pushing
> back on fixing this in Guile itself.

I don't know, it might not be that bad, now that we've agreed on a way
to extend the port structure in 2.0.  Maybe we could just have a "last
peek-char returned EOF" flag that would be consulted by the other read
primitives.

I agree that we should not allow EOF to be unread.

What do you think?

      Mark

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.