GNU bug report logs - #11887
string->number edge cases

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Ian Price <ianprice90 <at> googlemail.com>
Subject: bug#11887: closed (Re: bug#11887: [PATCH] Improve standards
 conformance of string->number (was Re: bug#11887: string->number edge
 cases))
Date: Thu, 07 Mar 2013 20:49:03 +0000

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Your bug report

#11887: string->number edge cases

which was filed against the guile package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 11887 <at> debbugs.gnu.org.

-- 
11887: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=11887
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Mark H Weaver <mhw <at> netris.org>
To: 11887-done <at> debbugs.gnu.org
Cc: Ian Price <ianprice90 <at> googlemail.com>
Subject: Re: bug#11887: [PATCH] Improve standards conformance of
	string->number (was Re: bug#11887: string->number edge cases)
Date: Thu, 07 Mar 2013 15:47:17 -0500

I wrote:
> Here's a patch to fix these problems.  Comments and suggestions welcome.

I went ahead and pushed this to stable-2.0.  I'm closing this bug.

    Thanks,
      Mark

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From: Ian Price <ianprice90 <at> googlemail.com>
To: bug-guile <at> gnu.org
Cc: Peter.Bex <at> xs4all.nl
Subject: string->number edge cases
Date: Mon, 09 Jul 2012 13:29:16 +0100

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Hi guilers,

I've mentioned these to Mark Weaver on IRC off-hand before, but I'm
posting this bug report to "formalise" it, and make sure we don't
forget.

Peter Bex, as one of the maintainers of the chicken "numbers" egg,
created a thorough test suite for string->number a while ago[0], and it
points out a number of possible and actual errors in the handling of
string->number.

I've attached a copy with the modifications for guile already applied,
and a copy of the full results, but the summary is as follows.

If the number contains a division by zero, we get a numerical overflow
error.

scheme@(guile−user)> (string->number "3/0")
ERROR: In procedure string−>number:
ERROR: Throw to key `numerical−overflow' with args `("make−ratio" "Numerical overflow" #f #f)'.

Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
scheme@(guile−user) [1]> ,q

This contradicts the r6rs specification[1], which mandates a return
value of #f. IMO, this is the correct behaviour, since otherwise, we
have created a special case in the API for one type of invalid number.

(These tests cause the program to stop, and so are commented out in the
attached version.)

The rest of the errors are less serious, and show that we treat nans and
infinity someone inconsistently in guile. Specifically, we are strict on
case, and lenient on the numerical prefix.

0. http://bugs.call-cc.org/browser/release/4/numbers/trunk/tests/string-conversion.scm
1. http://www.r6rs.org/final/html/r6rs/r6rs-Z-H-14.html#node_idx_584

Peter,

Thanks for these

-- 
Ian Price

"Programming is like pinball. The reward for doing it well is
the opportunity to do it again" - from "The Wizardy Compiled"

[string-conversion.scm (text/plain, attachment)]

[results.txt (text/plain, attachment)]

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