From: Stefan Monnier <monnier@IRO.UMontreal.CA>
To: Juanma Barranquero <lekktu@gmail.com>
Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org
Subject: Re: Inconsistency in `string-to-number'
Date: Tue, 01 Dec 2009 15:15:59 -0500 [thread overview]
Message-ID: <jwvhbsabglv.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <f7ccd24b0909041730j3ebfa3f4h5fc4728bb6301272@mail.gmail.com> (Juanma Barranquero's message of "Sat, 5 Sep 2009 02:30:39 +0200")
>> Actually it could also break code (tho it seems unlikely). I wouldn't
>> mind postponing the fix to Emacs-23.2. In the mean time, we need to
>> improve the docstring.
> The docstring was not improved, and we're now on the 23.2 track, so
> time for a reprieve.
Sorry, your email got misfiled.
> Reminder: The problem is the following inconsistency:
> (string-to-number "1:") => 1
> (string-to-number "1.2:") => 1
> (string-to-number "1.2") => 1.2
> Alas, the docstring talks about "leading spaces and tabs", but says
> nothing about trailing chars.
> Currently the behavior, depending of the first non-digit after the
> number, is as follows:
> - \0, \s, \r, \n, \f and \t => the number is read as a float (if
> base == 10) or integer, as intended.
> - Any other char: the number is always interpreted as an integer.
> Possibilities:
> 0) Do nothing except clarifying the docs.
> Pro: easier of all fixes.
> Cons: inconsistency.
That would be documenting a bad behavior, so that would only be
acceptable if the new doc says "if there's something after the number,
you're on your own".
> 1) Disallow any trailing char.
> Pro: follows the doc (sort of).
> Cons: incompatibility with current uses of undocumented "1:", etc.
That's not a good option, no. I know there is code out there in use
that relies on this behavior (I'm probably guilty myself), but I don't
know how to find it to fix it, so I'd rather stay away from this.
> 2) Allow only whitespace: the same chars that the float case admits right now.
> Pro: quite intuitive (IMO), easy to implement.
> Cons: Same as 1)
Indeed, same as above.
> 3) Allow any trailing char.
> Pro: forgiving.
> Cons: (unlikely) incompatibility with uses of undocumented "1.2:" => 1
That would be my choice. The behavior is still fairly regular, so the
doc shouldn't be too scary, and it works about as well as now.
> I like 2), because it seems cleaner to just allow whitespace all
> around the number; it has a certain risk of incompatibility, though.
> 1) and 3) would require adding a new parameter to
> lread.c:isfloat_string() or somesuch; not hard, but not very clean.
I'd need to see the patch to pronouce myself on the uncleanliness.
Stefan
next prev parent reply other threads:[~2009-12-01 20:15 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-24 0:16 Inconsistency in `string-to-number' Davis Herring
2009-04-24 10:36 ` Eli Zaretskii
2009-04-24 11:45 ` Juanma Barranquero
2009-04-24 13:19 ` Eli Zaretskii
2009-04-24 14:13 ` Juanma Barranquero
2009-04-24 13:22 ` Stefan Monnier
2009-04-24 13:38 ` Juanma Barranquero
2009-04-24 14:06 ` Stefan Monnier
2009-04-24 14:16 ` Juanma Barranquero
2009-09-05 0:30 ` Juanma Barranquero
2009-12-01 20:15 ` Stefan Monnier [this message]
2009-12-04 3:21 ` Juanma Barranquero
2009-12-04 3:23 ` Juanma Barranquero
2009-12-04 14:22 ` Stefan Monnier
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