GNU bug report logs - #24369
Docu of prefix-numeric-value

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Andreas Röhler <andreas.roehler <at> easy-emacs.de>
To: bug-gnu-emacs <at> gnu.org
Subject: Docu of prefix-numeric-value
Date: Mon, 5 Sep 2016 09:52:35 +0200

See recent question at

http://lists.gnu.org/archive/html/help-gnu-emacs/2016-09/msg00018.html

Please add some explanation WRT treatment of the nil-argument.

Also WRT C-u

Thanks!

Message #8 received at 24369 <at> debbugs.gnu.org (full text, mbox):

From: Drew Adams <drew.adams <at> oracle.com>
To: Andreas Röhler <andreas.roehler <at> easy-emacs.de>,
 24369 <at> debbugs.gnu.org
Subject: RE: bug#24369: Docu of prefix-numeric-value
Date: Mon, 5 Sep 2016 08:57:05 -0700 (PDT)

> See recent question at
> http://lists.gnu.org/archive/html/help-gnu-emacs/2016-09/msg00018.html
> 
> Please add some explanation WRT treatment of the nil-argument.
> Also WRT C-u

What "treatment" are you asking to be explained?
Just what do you think is missing?

Message #11 received at 24369 <at> debbugs.gnu.org (full text, mbox):

From: Andreas Röhler <andreas.roehler <at> easy-emacs.de>
To: Drew Adams <drew.adams <at> oracle.com>, 24369 <at> debbugs.gnu.org
Subject: Re: bug#24369: Docu of prefix-numeric-value
Date: Mon, 5 Sep 2016 19:44:28 +0200

On 05.09.2016 17:57, Drew Adams wrote:
>> See recent question at
>> http://lists.gnu.org/archive/html/help-gnu-emacs/2016-09/msg00018.html
>>
>> Please add some explanation WRT treatment of the nil-argument.
>> Also WRT C-u
> What "treatment" are you asking to be explained?
> Just what do you think is missing?

Elisp Info 20.2.2 Code Characters for ‘interactive’
----------------------------------------

p’
     The numeric prefix argument

User will expect the argument received by function being consistent with 
input, i.e. M-x 2 foo... sends 2, M-x 1 foo ... sends 1. From there 
omitting an argument will be expected to send nothing - which isn't the 
case.

Likewise with uppecase P.

Message #14 received at 24369 <at> debbugs.gnu.org (full text, mbox):

From: Drew Adams <drew.adams <at> oracle.com>
To: Andreas Röhler <andreas.roehler <at> easy-emacs.de>,
 24369 <at> debbugs.gnu.org
Subject: RE: bug#24369: Docu of prefix-numeric-value
Date: Mon, 5 Sep 2016 10:46:07 -0700 (PDT)

> > What "treatment" are you asking to be explained?
> > Just what do you think is missing?
> 
> Elisp Info 20.2.2 Code Characters for ‘interactive’
> ----------------------------------------
> 
> p  The numeric prefix argument
> 
> Likewise with uppecase P.

Again, what do you think is missing?  `p' is the numeric prefix argument.
`P' is the raw prefix argument.

This is not the Elisp manual node that describes WHAT these things
are.  But there is a link here to the node that does that, node
`Prefix Command Arguments'

http://www.gnu.org/software/emacs/manual/html_node/elisp/Prefix-Command-Arguments.html

And that's the case even in the Emacs 20 version of the manual,
which you cited.

> User will expect the argument received by function being consistent with
> input, i.e. M-x 2 foo... sends 2, M-x 1 foo ... sends 1. From there
> omitting an argument will be expected to send nothing - which isn't the
> case.

Why on Earth would the user expect that, simply from reading that
`interactive' code `p' returns the numeric prefix argument and `P'
returns the raw prefix argument?

Message #17 received at 24369 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Andreas Röhler <andreas.roehler <at> easy-emacs.de>
Cc: 24369 <at> debbugs.gnu.org, drew.adams <at> oracle.com
Subject: Re: bug#24369: Docu of prefix-numeric-value
Date: Mon, 05 Sep 2016 20:57:31 +0300

> From: Andreas Röhler <andreas.roehler <at> easy-emacs.de>
> Date: Mon, 5 Sep 2016 19:44:28 +0200
> 
> >> Please add some explanation WRT treatment of the nil-argument.
> >> Also WRT C-u
> > What "treatment" are you asking to be explained?
> > Just what do you think is missing?
> 
> Elisp Info 20.2.2 Code Characters for ‘interactive’
> ----------------------------------------
> 
> p’
>       The numeric prefix argument
> 
> User will expect the argument received by function being consistent with 
> input, i.e. M-x 2 foo... sends 2, M-x 1 foo ... sends 1. From there 
> omitting an argument will be expected to send nothing - which isn't the 
> case.

There's more in the manual than just that one paragraph.

ELisp manual 20.12 Prefix Command Arguments:
-------------------------------------------

   There are two representations of the prefix argument: “raw” and
“numeric”.  The editor command loop uses the raw representation
internally, and so do the Lisp variables that store the information, but
commands can request either representation.

   Here are the possible values of a raw prefix argument:

   • ‘nil’, meaning there is no prefix argument.  Its numeric value is
     1, but numerous commands make a distinction between ‘nil’ and the
     integer 1.
   ...


 -- Function: prefix-numeric-value arg
     This function returns the numeric meaning of a valid raw prefix
     argument value, ARG.  The argument may be a symbol, a number, or a
     list.  If it is ‘nil’, the value 1 is returned; if it is ‘-’, the
     value −1 is returned; if it is a number, that number is returned;
     if it is a list, the CAR of that list (which should be a number) is
     returned.

Message #20 received at 24369 <at> debbugs.gnu.org (full text, mbox):

From: Andreas Röhler <andreas.roehler <at> easy-emacs.de>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 24369 <at> debbugs.gnu.org, drew.adams <at> oracle.com
Subject: Re: bug#24369: Docu of prefix-numeric-value
Date: Mon, 5 Sep 2016 20:33:21 +0200

On 05.09.2016 19:57, Eli Zaretskii wrote:
>
>     Here are the possible values of a raw prefix argument:
>
>     • ‘nil’, meaning there is no prefix argument.  Its numeric value is
>       1,

That's the point:

Value of nil is 1
Value of 1 is 1

But he value of 2 is 2

Consistency means something different.

Message #23 received at 24369 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Andreas Röhler <andreas.roehler <at> easy-emacs.de>
Cc: 24369 <at> debbugs.gnu.org, drew.adams <at> oracle.com
Subject: Re: bug#24369: Docu of prefix-numeric-value
Date: Mon, 05 Sep 2016 21:57:58 +0300

> Cc: drew.adams <at> oracle.com, 24369 <at> debbugs.gnu.org
> From: Andreas Röhler <andreas.roehler <at> easy-emacs.de>
> Date: Mon, 5 Sep 2016 20:33:21 +0200
> 
> >     • ‘nil’, meaning there is no prefix argument.  Its numeric value is
> >       1,
> 
> That's the point:
> 
> Value of nil is 1

No, the _numeric_ value of nil is 1.  IOW, nil, when interpreted as a
number, is 1.  An entirely different story.

> Consistency means something different.

The numeric value of nil is consistently 1.

Message #26 received at 24369 <at> debbugs.gnu.org (full text, mbox):

From: Drew Adams <drew.adams <at> oracle.com>
To: Eli Zaretskii <eliz <at> gnu.org>, Andreas Röhler
 <andreas.roehler <at> easy-emacs.de>
Cc: 24369 <at> debbugs.gnu.org
Subject: RE: bug#24369: Docu of prefix-numeric-value
Date: Mon, 5 Sep 2016 14:03:17 -0700 (PDT)

> > >     • ‘nil’, meaning there is no prefix argument.  Its numeric value
> > >       is 1,
> >
> > That's the point: Value of nil is 1
> 
> No, the _numeric_ value of nil is 1.  IOW, nil, when interpreted
> as a number, is 1.  An entirely different story.

Exactly.  The value of `(prefix-numeric-value nil)' is 1.

That's what "numeric value of" the prefix argument means.
It is also what the shorter expression "the numeric prefix
argument" means.

The fact that the value of some function applied to nil
is 1 does not mean that the value of nil is 1.

Message #29 received at 24369 <at> debbugs.gnu.org (full text, mbox):

From: npostavs <at> users.sourceforge.net
To: Drew Adams <drew.adams <at> oracle.com>
Cc: Eli Zaretskii <eliz <at> gnu.org>,
 Andreas Röhler <andreas.roehler <at> easy-emacs.de>,
 24369 <at> debbugs.gnu.org
Subject: Re: bug#24369: Docu of prefix-numeric-value
Date: Sun, 16 Jul 2017 21:37:20 -0400

tags 24369 notabug
close 24369
quit

Drew Adams <drew.adams <at> oracle.com> writes:

>> > >     • ‘nil’, meaning there is no prefix argument.  Its numeric value
>> > >       is 1,
>> >
>> > That's the point: Value of nil is 1
>> 
>> No, the _numeric_ value of nil is 1.  IOW, nil, when interpreted
>> as a number, is 1.  An entirely different story.
>
> Exactly.  The value of `(prefix-numeric-value nil)' is 1.
>
> That's what "numeric value of" the prefix argument means.
> It is also what the shorter expression "the numeric prefix
> argument" means.
>
> The fact that the value of some function applied to nil
> is 1 does not mean that the value of nil is 1.

I think there is nothing more to be done here, so I'm closing the bug.

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