[debbugs-tracker] bug#12216: closed (peek-char incorrectly *CONSUMES* eof)

[GNU bug Tracking System]

Your message dated Thu, 04 Apr 2013 17:53:50 -0400
with message-id <address@hidden>
and subject line Re: bug#12216: peek-char incorrectly *CONSUMES* eof
has caused the debbugs.gnu.org bug report #12216,
regarding peek-char incorrectly *CONSUMES* eof
to be marked as done.

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-- 
12216: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=12216
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> --- Begin Message ---
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> Subject: 
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> peek-char incorrectly *CONSUMES* eof
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> Date: 
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> Thu, 16 Aug 2012 21:53:23 -0400 (EDT)
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> All:
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> Guile's peek-char has a bug; it incorrectly *consumes* eof instead of just 
> reporting it.
>
> According to R5RS, "The value returned by a call to peek-char is the same as 
> the value that would have been returned by a call to read-char with the same 
> port. The only difference is that the very next call to read-char or peek-char 
> on that port will return the value returned by the preceding call to peek-char."
>
> However, if the value returned is #eof, guile does *not* meet the spec; you 
> *can* get two successive peek-chars with different results.
>
> This doesn't matter for files, but it *does* matter for interactive use.  It 
> means that successive peek-char calls will actually *READ* characters, and they 
> can even different in results.  Which means that code that does several 
> peek-chars can act oddly when someone tries to end it with control-D.
>
> We've confirmed this bug is true for guile 2.0, 1.8, and 1.6.
>
> You can confirm this by placing this in "bug-demo":
> ===================
> (write (peek-char))
> (write (peek-char))
> ======================
>
> Then run "guile bug-demo".  Press control-D, then newline.  You can see that 
> two successive calls to peek-char are reporting different results (eof, then 
> newline), which is NEVER supposed to happen!
>
> I just had to write some code to work around this, but it'd be nice for this to 
> work "correctly" in the future for interactive use.  (This was code for the 
> "readable" project, http://readable.sourceforge.net, where we do a lot with 
> guile.)
>
> Thanks for your time... and thanks for guile!
>
> --- David A. Wheeler
>
>
>
> --- End Message ---
> --- Begin Message ---
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>
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> Subject: 
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> Re: bug#12216: peek-char incorrectly *CONSUMES* eof
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>
>
>
> Date: 
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> Thu, 04 Apr 2013 17:53:50 -0400
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> User-agent: 
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> Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux)
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>
> Andy Wingo <address@hidden> writes:
> > Looks great to me.  Thanks for following up on this!
>
> Excellent!  I pushed this to stable-2.0, so it will be in Guile 2.0.8.
> Closing this bug now.
>
>     Thanks!
>       Mark
>
>
> --- End Message ---