* Re: doc string of `format' - FLAGS unexplained
[not found] <003c01c8767e$115f1520$0600a8c0@us.oracle.com>
@ 2008-02-25 23:13 ` Chong Yidong
2008-02-25 23:27 ` Andreas Schwab
2008-02-26 0:05 ` Lennart Borgman (gmail)
0 siblings, 2 replies; 6+ messages in thread
From: Chong Yidong @ 2008-02-25 23:13 UTC (permalink / raw)
To: emacs-devel
"Drew Adams" <drew.adams@oracle.com> writes:
> The doc string includes this:
>
> The basic structure of a %-sequence is
> % <flags> <width> <precision> character
> where flags is [-+ #0]+, width is [0-9]+, and precision is .[0-9]+
>
> But there is absolutely no explanation of what FLAGS, WIDTH, and
> PRECISION mean. One might be able to guess for WIDTH and PRECISION,
> but not for FLAGS. Please include some of the explanation from the
> Elisp manual, adapting it as needed.
>
> Also, the EMACS convention for doc strings is to use uppercase: FLAGS,
> not angle brackets: <flags>.
I'd like to propose the following change to the doc string of
`format'.
In particular, the statement "flags is [-+ #0]+" is misleading; it
should be [+ #]+, since the - and 0 characters are actually used to
identify the width specifier instead.
Any thoughts?
*** emacs/src/editfns.c.~1.439.2.10.~ 2008-01-10 10:26:25.000000000 -0500
--- emacs/src/editfns.c 2008-02-25 18:12:57.000000000 -0500
***************
*** 3383,3389 ****
doc: /* Format a string out of a format-string and arguments.
The first argument is a format control string.
The other arguments are substituted into it to make the result, a string.
! It may contain %-sequences meaning to substitute the next argument.
%s means print a string argument. Actually, prints any object, with `princ'.
%d means print as number in decimal (%o octal, %x hex).
%X is like %x, but uses upper case.
--- 3383,3392 ----
doc: /* Format a string out of a format-string and arguments.
The first argument is a format control string.
The other arguments are substituted into it to make the result, a string.
!
! The format control string may contain %-sequences meaning to substitute
! the next available argument:
!
%s means print a string argument. Actually, prints any object, with `princ'.
%d means print as number in decimal (%o octal, %x hex).
%X is like %x, but uses upper case.
***************
*** 3393,3404 ****
or decimal-point notation, whichever uses fewer characters.
%c means print a number as a single character.
%S means print any object as an s-expression (using `prin1').
! The argument used for %d, %o, %x, %e, %f, %g or %c must be a number.
Use %% to put a single % into the output.
! The basic structure of a %-sequence is
! % <flags> <width> <precision> character
! where flags is [-+ #0]+, width is [0-9]+, and precision is .[0-9]+
usage: (format STRING &rest OBJECTS) */)
(nargs, args)
--- 3396,3428 ----
or decimal-point notation, whichever uses fewer characters.
%c means print a number as a single character.
%S means print any object as an s-expression (using `prin1').
!
! The argument used for %d, %o, %x, %e, %f, %g or %c must be a number.
Use %% to put a single % into the output.
! A %-sequence may contain optional flag, width, and precision
! specifiers, as follows:
!
! %<flags><width><precision>character
!
! where flags is [+ #]+, width is [0-9]+, and precision is .[0-9]+
!
! The + flag character inserts a + before any positive number, while a
! space inserts a space before any positive number; these flags only
! affect %d, %e, %f, and %g sequences, and + takes precedence if both
! flags are present. The # flag means to use an alternate display form
! for %o, %x, %X, %e, %f, and %g sequences.
!
! The width specifier supplies a lower limit for the length of the
! printed representation. The padding, if any, goes on the left if the
! width specifier is positive or starts with a 0, and on the right if it
! is negative. The padding character is normally a space, and 0 if the
! width specifier starts with the character 0.
!
! For %e, %f, and %g sequences, the number after the "." in the
! precision specifier says how many decimal places to show; if zero, the
! decimal point itself is omitted. For %s and %S, the precision
! specifier truncates the string to the given width.
usage: (format STRING &rest OBJECTS) */)
(nargs, args)
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: doc string of `format' - FLAGS unexplained
2008-02-25 23:13 ` doc string of `format' - FLAGS unexplained Chong Yidong
@ 2008-02-25 23:27 ` Andreas Schwab
2008-02-26 0:23 ` Chong Yidong
2008-02-26 0:05 ` Lennart Borgman (gmail)
1 sibling, 1 reply; 6+ messages in thread
From: Andreas Schwab @ 2008-02-25 23:27 UTC (permalink / raw)
To: Chong Yidong; +Cc: emacs-devel
Chong Yidong <cyd@stupidchicken.com> writes:
> In particular, the statement "flags is [-+ #0]+" is misleading; it
> should be [+ #]+, since the - and 0 characters are actually used to
> identify the width specifier instead.
This is wrong. '-' and '0' are real flags that can be freely mixed with
other flags, eg. "%0#10d" is valid and the same as "%#010d". They are
never considered part of the width.
Andreas.
--
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: doc string of `format' - FLAGS unexplained
2008-02-25 23:13 ` doc string of `format' - FLAGS unexplained Chong Yidong
2008-02-25 23:27 ` Andreas Schwab
@ 2008-02-26 0:05 ` Lennart Borgman (gmail)
1 sibling, 0 replies; 6+ messages in thread
From: Lennart Borgman (gmail) @ 2008-02-26 0:05 UTC (permalink / raw)
To: Chong Yidong; +Cc: emacs-devel
Chong Yidong wrote:
> I'd like to propose the following change to the doc string of
> `format'.
>
> In particular, the statement "flags is [-+ #0]+" is misleading; it
> should be [+ #]+, since the - and 0 characters are actually used to
> identify the width specifier instead.
>
> Any thoughts?
How nice with a readable description of those formats. But
> ! %<flags><width><precision>character
> !
> ! where flags is [+ #]+, width is [0-9]+, and precision is .[0-9]+
! where <flags> is [+ #0]+, width is [1-9][0-9]*, and precision is
.[0-9]+
is perhaps more accurate. `0' is a flag that gives leading 0:s, isn't it?
And perhaps is it more logical to write <flags> then just flags?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: doc string of `format' - FLAGS unexplained
2008-02-25 23:27 ` Andreas Schwab
@ 2008-02-26 0:23 ` Chong Yidong
2008-02-26 12:07 ` Andreas Schwab
0 siblings, 1 reply; 6+ messages in thread
From: Chong Yidong @ 2008-02-26 0:23 UTC (permalink / raw)
To: Andreas Schwab; +Cc: emacs-devel
Andreas Schwab <schwab@suse.de> writes:
> Chong Yidong <cyd@stupidchicken.com> writes:
>
>> In particular, the statement "flags is [-+ #0]+" is misleading; it
>> should be [+ #]+, since the - and 0 characters are actually used to
>> identify the width specifier instead.
>
> This is wrong. '-' and '0' are real flags that can be freely mixed with
> other flags, eg. "%0#10d" is valid and the same as "%#010d". They are
> never considered part of the width.
The question is, do we regard this as an undocumented side-effect of
the implementation? Treating '-' and '0' as part of the width
specifier is conceptually simpler, and the elisp manual documents
these as such. If we treat '0' as a real flag, then maybe the
description in the elisp manual should be revised.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: doc string of `format' - FLAGS unexplained
2008-02-26 0:23 ` Chong Yidong
@ 2008-02-26 12:07 ` Andreas Schwab
2008-02-26 16:33 ` Chong Yidong
0 siblings, 1 reply; 6+ messages in thread
From: Andreas Schwab @ 2008-02-26 12:07 UTC (permalink / raw)
To: Chong Yidong; +Cc: emacs-devel
Chong Yidong <cyd@stupidchicken.com> writes:
> Andreas Schwab <schwab@suse.de> writes:
>
>> Chong Yidong <cyd@stupidchicken.com> writes:
>>
>>> In particular, the statement "flags is [-+ #0]+" is misleading; it
>>> should be [+ #]+, since the - and 0 characters are actually used to
>>> identify the width specifier instead.
>>
>> This is wrong. '-' and '0' are real flags that can be freely mixed with
>> other flags, eg. "%0#10d" is valid and the same as "%#010d". They are
>> never considered part of the width.
>
> The question is, do we regard this as an undocumented side-effect of
> the implementation?
It works the same as in C, which is widely understood. Gratuitous
differences only confuse people.
Andreas.
--
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: doc string of `format' - FLAGS unexplained
2008-02-26 12:07 ` Andreas Schwab
@ 2008-02-26 16:33 ` Chong Yidong
0 siblings, 0 replies; 6+ messages in thread
From: Chong Yidong @ 2008-02-26 16:33 UTC (permalink / raw)
To: Andreas Schwab; +Cc: emacs-devel
Andreas Schwab <schwab@suse.de> writes:
> Chong Yidong <cyd@stupidchicken.com> writes:
>
>> Andreas Schwab <schwab@suse.de> writes:
>>
>>> Chong Yidong <cyd@stupidchicken.com> writes:
>>>
>>>> In particular, the statement "flags is [-+ #0]+" is misleading; it
>>>> should be [+ #]+, since the - and 0 characters are actually used to
>>>> identify the width specifier instead.
>>>
>>> This is wrong. '-' and '0' are real flags that can be freely mixed with
>>> other flags, eg. "%0#10d" is valid and the same as "%#010d". They are
>>> never considered part of the width.
>>
>> The question is, do we regard this as an undocumented side-effect of
>> the implementation?
>
> It works the same as in C, which is widely understood. Gratuitous
> differences only confuse people.
True enough. I've checked in a corrected docstring that treats - and
0 as flags.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2008-02-26 16:33 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
[not found] <003c01c8767e$115f1520$0600a8c0@us.oracle.com>
2008-02-25 23:13 ` doc string of `format' - FLAGS unexplained Chong Yidong
2008-02-25 23:27 ` Andreas Schwab
2008-02-26 0:23 ` Chong Yidong
2008-02-26 12:07 ` Andreas Schwab
2008-02-26 16:33 ` Chong Yidong
2008-02-26 0:05 ` Lennart Borgman (gmail)
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).