tabs v spaces in Emacs's source files

tabs v spaces in Emacs's source files

[Glenn Morris]

Is there a convention on whether tabs or spaces should be used to
indent Emacs's source files, or is it up to the maintainer of a given
file? I don't want to propose one or the other, just ask if there's a
standard.

Re: tabs v spaces in Emacs's source files

[Miles Bader]

Glenn Morris <rgm@gnu.org> writes:
> Is there a convention on whether tabs or spaces should be used to
> indent Emacs's source files, or is it up to the maintainer of a given
> file? I don't want to propose one or the other, just ask if there's a
> standard.

Generally it's both.  I've noticed some files use mainly spaces,
presumably because the original author did, but over time things to fuzz
out as people with different settings edit the code.  Mostly it doesn't
really matter I think....

-Miles

-- 
In New York, most people don't have cars, so if you want to kill a person, you
have to take the subway to their house.  And sometimes on the way, the train
is delayed and you get impatient, so you have to kill someone on the subway.
  [George Carlin]

Re: tabs v spaces in Emacs's source files

[Andreas Schwab]

Glenn Morris <rgm@gnu.org> writes:

> Is there a convention on whether tabs or spaces should be used to
> indent Emacs's source files, or is it up to the maintainer of a given
> file? I don't want to propose one or the other, just ask if there's a
> standard.

The Emacs source should generally follow the GNU Coding Standards
<http://www.gnu.org/prep/standards/>.

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."

Re: tabs v spaces in Emacs's source files

[Juanma Barranquero]

On Fri, Mar 7, 2008 at 11:19 AM, Andreas Schwab <schwab@suse.de> wrote:

>  The Emacs source should generally follow the GNU Coding Standards
>  <http://www.gnu.org/prep/standards/>.

Where does it say whether to use tabs or spaces? (I never seem to find
that section.)

Whatever the coding guidelines says, an extremely informal count
suggests that of the non-empty lines with start with an indentation >=
8, about 8% of them use spaces in C code, and about 16% use spaces in
elisp code. So tab use is most common, but there are enough spaces
(we're talking literaly about tens of thousands of lines) to suggest
that Miles is right: it doesn't really matter...

             Juanma

Re: tabs v spaces in Emacs's source files

[Pete Forman]

"Juanma Barranquero" <lekktu@gmail.com> writes:

 > On Fri, Mar 7, 2008 at 11:19 AM, Andreas Schwab <schwab@suse.de> wrote:
>
>>  The Emacs source should generally follow the GNU Coding Standards
>>  <http://www.gnu.org/prep/standards/>.
>
 > Where does it say whether to use tabs or spaces? (I never seem to find
 > that section.)

http://www.gnu.org/prep/standards/html_node/Errors.html#Errors

That is talking about compiler messages and column numbers.  Working
backwards, that implies that source files may contain hard tabs, which
are size 8.  I did not see anything which says which says whether hard
tabs _should_ be used or not.
-- 
Pete Forman                -./\.-  Disclaimer: This post is originated
WesternGeco                  -./\.-   by myself and does not represent
pete.forman@westerngeco.com    -./\.-   the opinion of Schlumberger or
http://petef.22web.net          -./\.-   WesternGeco.

Re: tabs v spaces in Emacs's source files

[Juanma Barranquero]

On Fri, Mar 7, 2008 at 1:28 PM, Pete Forman <pete.forman@westerngeco.com> wrote:

>  That is talking about compiler messages and column numbers.  Working
>  backwards, that implies that source files may contain hard tabs, which
>  are size 8.  I did not see anything which says which says whether hard
>  tabs _should_ be used or not.

Which, alas, adds no information: in absence of explicit guidelines,
it should be safe to assume that either spaces or tabs can be used...

Thanks for finding that paragraph, though.

             Juanma

Re: tabs v spaces in Emacs's source files

[Johan Bockgård]

"Juanma Barranquero" <lekktu@gmail.com> writes:

> Which, alas, adds no information: in absence of explicit guidelines,
> it should be safe to assume that either spaces or tabs can be used...

Is this explicit enough?

    * Indent each function with `C-M-q' (`indent-sexp') using the
      default indentation parameters.

(info "(elisp) Coding Conventions")

-- 
Johan Bockgård

Re: tabs v spaces in Emacs's source files

[Juanma Barranquero]

On Fri, Mar 7, 2008 at 4:02 PM, Johan Bockgård
<bojohan+news@dd.chalmers.se> wrote:

>  Is this explicit enough?
>
>     * Indent each function with `C-M-q' (`indent-sexp') using the
>       default indentation parameters.
>
>  (info "(elisp) Coding Conventions")

Not really. Even if "default indentation parameters" means using
`indent-tabs-mode' set to t, that does not talk about the C code and
`c-indent-sexp'.

But anyway, the point is that there's a lot of code using spaces. If
there's a real interest in using only tabs, I'd suggest start adding
indent-tabs-mode cookies to local variables sections.

             Juanma

Re: tabs v spaces in Emacs's source files

[Karl Fogel]

"Juanma Barranquero" <lekktu@gmail.com> writes:
> But anyway, the point is that there's a lot of code using spaces. If
> there's a real interest in using only tabs, I'd suggest start adding
> indent-tabs-mode cookies to local variables sections.

I very much prefer spaces, because they're diff-safe (for example, in
commit emails).

With TABs, an unlucky indentation boundary can cause code to jump many
display columns to the right, due to the "+"/"-" column along the left
edge of the diff.  This makes reading diffs of TAB-indented code a dicey
game.

-Karl

Re: tabs v spaces in Emacs's source files

[Juanma Barranquero]

On Fri, Mar 7, 2008 at 6:11 PM, Karl Fogel <kfogel@red-bean.com> wrote:

>  I very much prefer spaces, because they're diff-safe (for example, in
>  commit emails).

I do too. I have indent-tabs-mode set to nil, and I have code in my
.emacs to detect when I'm editing Emacs source code so it can be
locally set to t.

             Juanma

Re: tabs v spaces in Emacs's source files

[Eli Zaretskii]

> From: Karl Fogel <kfogel@red-bean.com>
> Date: Fri, 07 Mar 2008 12:11:36 -0500
> Cc: emacs-devel@gnu.org
> 
> "Juanma Barranquero" <lekktu@gmail.com> writes:
> > But anyway, the point is that there's a lot of code using spaces. If
> > there's a real interest in using only tabs, I'd suggest start adding
> > indent-tabs-mode cookies to local variables sections.
> 
> I very much prefer spaces, because they're diff-safe (for example, in
> commit emails).

Whatever people prefer, we should IMO use a consistent indentation
rules in Emacs.  Personally, I prefer the Emacs defaults, but if the
head maintainers prefer a different scheme, I will not object.

In any case, the current situation of inconsistent use of spaces and
TABs is IMO much worse than any of the consistent alternatives.
AFAIU, the GNU Coding Standards call for consistency wrt issues of
style:

       The rest of this section gives our recommendations for other aspects
    of C formatting style, which is also the default style of the `indent'
    program in version 1.2 and newer.  It corresponds to the options

	 -nbad -bap -nbc -bbo -bl -bli2 -bls -ncdb -nce -cp1 -cs -di2
	 -ndj -nfc1 -nfca -hnl -i2 -ip5 -lp -pcs -psl -nsc -nsob

       We don't think of these recommendations as requirements, because it
    causes no problems for users if two different programs have different
    formatting styles.

       But whatever style you use, please use it consistently, since a
    mixture of styles within one program tends to look ugly.  If you are
    contributing changes to an existing program, please follow the style of
    that program.

Re: tabs v spaces in Emacs's source files

[Stefan Monnier]

> Whatever people prefer, we should IMO use a consistent indentation
> rules in Emacs.

space-vs-tabs-vs-aliens doesn't matter, as long as it's indented to the
right position.  That's my opinion on this matter.

> In any case, the current situation of inconsistent use of spaces and
> TABs is IMO much worse than any of the consistent alternatives.

It's completely irrelevant and a waste of time to even discuss it.
Please stop,


        Stefan

Re: tabs v spaces in Emacs's source files

[Bill Wohler]

Karl Fogel <kfogel@red-bean.com> writes:

> "Juanma Barranquero" <lekktu@gmail.com> writes:
>> But anyway, the point is that there's a lot of code using spaces. If
>> there's a real interest in using only tabs, I'd suggest start adding
>> indent-tabs-mode cookies to local variables sections.
>
> I very much prefer spaces, because they're diff-safe (for example, in
> commit emails).
>
> With TABs, an unlucky indentation boundary can cause code to jump many
> display columns to the right, due to the "+"/"-" column along the left
> edge of the diff.  This makes reading diffs of TAB-indented code a dicey
> game.

In addition to generating unreadable diffs, tabbed programs also
produce unreadable output in a terminal window or when printed.

spaces *= Integer.MAX_VALUE;

-- 
Bill Wohler <wohler@newt.com>  http://www.newt.com/wohler/  GnuPG ID:610BD9AD

Re: tabs v spaces in Emacs's source files

[Miles Bader]

Bill Wohler <wohler@newt.com> writes:
>> With TABs, an unlucky indentation boundary can cause code to jump many
>> display columns to the right, due to the "+"/"-" column along the left
>> edge of the diff.  This makes reading diffs of TAB-indented code a dicey
>> game.
>
> In addition to generating unreadable diffs, tabbed programs also
> produce unreadable output in a terminal window or when printed.

Are we done with the silly hyperbole now?

-Miles

-- 
Faith, n. Belief without evidence in what is told by one who speaks without
knowledge, of things without parallel.

Re: tabs v spaces in Emacs's source files

[Richard Stallman]

    In addition to generating unreadable diffs, tabbed programs also
    produce unreadable output in a terminal window or when printed.

If you are trying to argue for eliminating tabs in GNU source code,
I certainly won't do that, so there is no use arguing for it.
Please understand that this question is already decided.

RE: tabs v spaces in Emacs's source files

[Drew Adams]

I don't know whether the coding standard is strict in preferring TAB
characters, or why it would be. And I don't know if it is cast in concrete
or is open to suggestions. When we post patches, we generally create them
using `diff -c -w' AFAIK, which would seem to suggest an agnostic (or at
least a loose) approach to indenting whitespace.

FWIW, I prefer to work with code that uses TAB characters only where they
are pertinent - e.g. in strings. IOW, I use spaces for indenting. Turning on
highlighting of TAB chars then shows me only the places where a TAB
character is really important. I like those TABS to stand out; I don't like
the noise that comes from TABs used just to indent code. Just one opinion.

Re: tabs v spaces in Emacs's source files

[Eli Zaretskii]

> From: "Drew Adams" <drew.adams@oracle.com>
> Date: Fri, 7 Mar 2008 09:21:55 -0800
> 
> When we post patches, we generally create them
> using `diff -c -w' AFAIK, which would seem to suggest an agnostic (or at
> least a loose) approach to indenting whitespace.

Actually, you should drop the -w when you generate patches, because it
causes trouble for Patch (unless the -l switch to Patch is used, which
is easily forgotten).

RE: tabs v spaces in Emacs's source files

[Drew Adams]

> > When we post patches, we generally create them
> > using `diff -c -w' AFAIK, which would seem to suggest an 
> > agnostic (or at least a loose) approach to indenting whitespace.
> 
> Actually, you should drop the -w when you generate patches, because it
> causes trouble for Patch (unless the -l switch to Patch is used, which
> is easily forgotten).

Really? I seem to recall someone mentioning here that -c -w was what was
preferred.

Re: tabs v spaces in Emacs's source files

[Stefan Monnier]

>> > When we post patches, we generally create them
>> > using `diff -c -w' AFAIK, which would seem to suggest an 
>> > agnostic (or at least a loose) approach to indenting whitespace.
>> 
>> Actually, you should drop the -w when you generate patches, because it
>> causes trouble for Patch (unless the -l switch to Patch is used, which
>> is easily forgotten).

> Really? I seem to recall someone mentioning here that -c -w was what was
> preferred.

I generally prefer "-u -w" when it's a patch for review.
And "-u" when it's a request to apply the patch.


        Stefan

Re: tabs v spaces in Emacs's source files

[Richard Stallman]

    Is there a convention on whether tabs or spaces should be used to
    indent Emacs's source files, or is it up to the maintainer of a given
    file? I don't want to propose one or the other, just ask if there's a
    standard.

You may as well always tabs, since they save space, and avoiding them
in any one file does no good.

Texinfo files are an exception; they are input for TeX so they should
not have tabs.  Texinfo mode takes care of that.