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

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Message #35 received at 12216 <at> debbugs.gnu.org (full text, mbox):

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: Re: 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

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