ice-9 lineio read-char versus unread-string

ice-9 lineio read-char versus unread-string

[Kevin Ryde]

In guile 1.6.3 on a recent i386 debian I was nosing around ice-9
lineio and struck an apparent problem with read-char used after an
unread-string.  For instance a program foo.scm

	(use-modules (ice-9 lineio))
	(let ((port (make-line-buffering-input-port
	             (open-input-string "hello"))))
	  (unread-string "world" port)
	  (display (read-char port)) (newline))

run "guile -s foo.scm" produces

  ERROR: Wrong number of arguments to #<primitive-procedure string-ref>

whereas I hoped it would print a character.

I guess this is just a missing index for the string-ref call in the
getc handler of make-line-buffering-input-port.  Judging by the
substring taken I guess it should be 0.


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Re: ice-9 lineio read-char versus unread-string

[Marius Vollmer]

Kevin Ryde <user42@zip.com.au> writes:

> I guess this is just a missing index for the string-ref call in the
> getc handler of make-line-buffering-input-port.  Judging by the
> substring taken I guess it should be 0.

Right.  Fixed in both branches, although I think the code hasn't
been used for three years or so...

The (ice-9 lineio) module was there to fix a deficiency in the core
ports and the original author expected it to be removed somewhen.
Maybe we should just do that.  Anybody?

-- 
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Re: ice-9 lineio read-char versus unread-string

[Neil Jerram]

>>>>> "Marius" == Marius Vollmer <mvo@zagadka.de> writes:

    Marius> Kevin Ryde <user42@zip.com.au> writes:
    >> I guess this is just a missing index for the string-ref call in the
    >> getc handler of make-line-buffering-input-port.  Judging by the
    >> substring taken I guess it should be 0.

    Marius> Right.  Fixed in both branches, although I think the code hasn't
    Marius> been used for three years or so...

    Marius> The (ice-9 lineio) module was there to fix a deficiency in the core
    Marius> ports and the original author expected it to be removed somewhen.
    Marius> Maybe we should just do that.  Anybody?

The (poor) comment doesn't say what that deficiency was.  Does anyone
know?  And if so, has it been fixed?

If no one knows, I support removing this from Guile core.

        Neil



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Re: ice-9 lineio read-char versus unread-string

[Marius Vollmer]

Neil Jerram <neil@ossau.uklinux.net> writes:

> The (poor) comment doesn't say what that deficiency was.  Does anyone
> know?  And if so, has it been fixed?

I have to say I don't understand what the purpose of lineio is and in
what way the core ports should be fixed.

I think we should deprecate the whole (ice-9 lineio) module.


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Re: ice-9 lineio read-char versus unread-string

[Paul Jarc]

Neil Jerram <neil@ossau.uklinux.net> wrote:
>>>>>> "Marius" == Marius Vollmer <mvo@zagadka.de> writes:
>     Marius> The (ice-9 lineio) module was there to fix a deficiency in the core
>     Marius> ports and the original author expected it to be removed somewhen.
>     Marius> Maybe we should just do that.  Anybody?
>
> The (poor) comment doesn't say what that deficiency was.  Does anyone
> know?  And if so, has it been fixed?

The functionality of (ice-9 lineio) is duplicated in the built-in
unread-string and the (ice-9 rdelim) module.  So, not knowing the
actual history, I would guess that (ice-9 lineio) predates them.  In
that case, now that we have those two, it would seem that lineio is no
longer needed.


paul


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