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Re: integer overflow handling for most-negative-fixnum
From: |
Helmut Eller |
Subject: |
Re: integer overflow handling for most-negative-fixnum |
Date: |
Sat, 21 Jul 2018 22:10:39 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
On Sat, Jul 21 2018, Paul Eggert wrote:
> How about this idea. First, we extend 'format' to support bitwidth
> modifiers for twos-complement representation. For example, (format
> "%/24x" -1) would format just the low-order 24 bits of the integer,
> and would return "ffffff" regardless of machine word size or whether
> bignums are used.
That sounds reasonable.
> Second, we change (format "%x" -1) to return "-1" rather than a
> machine-dependent string like "3fffffffffffffff" as it does now. That
> would make Elisp be more machine-independent, would solve Andy's
> problem, and would solve other problems once we have bignums, and in
> hindsight it's what we should have done originally.
Can't you simply use some other character for this, like %z (or %ℤ) and
leave %x alone. BTW, %i also seems to be a valid format specifier but
where is it documented?
> However, it would
> be an incompatible change, so let's have the behavior depend on a
> compatibility variable, much as we already do for
> read-integer-overflow-as-float.
This sounds more like that other desaster: text-quoting-style.
Helmut
- Re: integer overflow handling for most-negative-fixnum, (continued)
- Re: integer overflow handling for most-negative-fixnum, Helmut Eller, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Andy Moreton, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Eli Zaretskii, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Andy Moreton, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Stefan Monnier, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Paul Eggert, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Stefan Monnier, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Paul Eggert, 2018/07/23
- Re: integer overflow handling for most-negative-fixnum, Stefan Monnier, 2018/07/23
- Re: integer overflow handling for most-negative-fixnum, Paul Eggert, 2018/07/23
- Re: integer overflow handling for most-negative-fixnum,
Helmut Eller <=
- Re: integer overflow handling for most-negative-fixnum, Helmut Eller, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Paul Eggert, 2018/07/23
- Re: integer overflow handling for most-negative-fixnum, Eli Zaretskii, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Paul Eggert, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Eli Zaretskii, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Stefan Monnier, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Eli Zaretskii, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Stefan Monnier, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Helmut Eller, 2018/07/21
- Re: integer overflow handling for most-negative-fixnum, Paul Eggert, 2018/07/21