Tab or spaces: Emacs and Vim modelines are inconsistent

[cyrilbouvier]

I did not know where to put this issue as it concerns givaro, fflas and linbox.

Regarding the issues of usings tabs or spaces for indentation, the modelines present at the end of most source code files (embedded config for emacs and vim) are inconstistent:

In Emacs, the name of the setting is indent-tabs-mode:

• indent-tabs-mode: t: use tabs for indentation
• indent-tabs-mode: nil: use spaces for indentation

In Vim, the name of the setting is expandtab:

• noexpandtab or noet: (default) use tabs
• expandtab or et: do not use tabs [ tabs are expanded into spaces ]

All givaro files with Emacs modelines have indent-tabs-mode: t. Most fflas files with Emacs modelines have indent-tabs-mode: t, but some contain indent-tabs-mode: nil. All linbox files with Emacs modelines have indent-tabs-mode: nil

All givaro files with Vim modelines have noet. All fflas files with Vim modelines have noet. All but one linbox files with Vim modelines have et

Some files have one config for Emacs and the opposite for Vim (two example are benchmarks/benchmark-fsytrf.C in fflas and linbox/ring/polynomial-local-x.h in linbox)

There are similar inconsistencies regarding how many spaces should be used to replace tabs (8 or 4).

I do not know what is the space/tabs policy for the source files and what should be done about these inconsistencies.

[jgdumas]

I suggest to use tabs everywhere.

[Breush]

I'd vote for spaces instead. But I don't really care. Configuring editors so that it keeps the ident style of the files you're modifying would be great. Don't know if that's easy for everybody.

Otherwise, does emacs/vim can understand editorconfig file? (editorconfig.org) Could be a way to ensure global configuration for new developers.

[ClementPernet]

After some discussions, we agreed a while ago to the setting:

• no tabs
• indent width=4 I've been updating each file of fflas-ffpack and linbox that I was visiting for other topics) accordingly, but this is incremental and slow, hence it may still look inconsistent.

While tabs may seem better suited for indentation, I think spaces are much more suited for multiple users/config editing the same file.

Another argument for spaces: https://stackoverflow.blog/2017/06/15/developers-use-spaces-make-money-use-tabs/

[jgdumas]

ok for me (and I will ask for a raise ;-).

[bdsaunders]

Argh, I use tabs all over the place. Can you make it so that vi gives 4 spaces when I press tab (this doesn't cover all uses...)?

It's good to know why we make no money on LinBox.

On Wed, Feb 6, 2019 at 4:24 AM Jean-Guillaume Dumas < notifications@github.com> wrote:

ok for me (and I will ask for a raise ;-).

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[P1K]

On vim (vi too?): set tabstop=4 set expandtab should work. I don't know if there's a way to put something at the top of a file to override the .vimrc's settings; that'd be handy.

[vneiger]

I don't know if there's a way to put something at the top of a file to override the .vimrc's settings; that'd be handy.

As far as I understand that's the role of the modeline at the end of the file. And the modeline for vim which seems to be in most files in LinBox (didn't check fflas-ffpack) precisely does this choice (tab = 4 spaces, expand tab, etc), this modeline is: // vim:sts=4:sw=4:ts=4:et:sr:cino=>s,f0,{0,g0,(0,\:0,t0,+0,=s

[bdsaunders]

Thanks. I put those settings in my own .vimrc. If someone also makes it so in the settings at the bottom of the files, all to the good.

I hereby switch my beverage from Tab to Diet Tab.

On Wed, Feb 6, 2019 at 12:28 PM Pierre notifications@github.com wrote:

On vim (vi too?): set tabstop=4 set expandtab should work. I don't know if there's a way to put something at the top of a file to override the .vimrc's settings; that'd be handy.

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[P1K]

I don't know if there's a way to put something at the top of a file to override the .vimrc's settings; that'd be handy.

As far as I understand that's the role of the modeline at the end of the file. And the modeline for vim which seems to be in most files in LinBox (didn't check fflas-ffpack) precisely does this choice (tab = 4 spaces, expand tab, etc), this modeline is: // vim:sts=4:sw=4:ts=4:et:sr:cino=>s,f0,{0,g0,(0,\:0,t0,+0,=s

Indeed, thanks for the tip! Tho I actually had to change my .vimrc for this to be taken into account: set modeline set modelines=5 (or more; depends how far those comments are located) did the trick.

[P1K]

(But the modeline of fflas is quite different: // vim:sts=8:sw=8:ts=8:noet:sr:cino=>s,f0,{0,g0,(0,\:0,t0,+0,=s So tabs are real tabs and 8-space wide :P

[vneiger]

Ouch... I thought there was some discussion on the tabs/spaces and the modelines had been unified by someone (Dan ?) last Winter, and care was taken to put the vim one on the last line... but maybe that was just in LinBox. If everyone agrees on the modelines, it shouldn't take too long to copy them in all files (although not the most exciting task, I agree). I could do it if no one else volunteers.

The complete modelines used in LinBox:

// Local Variables:
// mode: C++
// tab-width: 4
// indent-tabs-mode: nil
// c-basic-offset: 4
// End:
// vim:sts=4:sw=4:ts=4:et:sr:cino=>s,f0,{0,g0,(0,\:0,t0,+0,=s

[P1K]

I can help too.

[vneiger]

Ok, I'll see if it takes longer than expected then I will tell you, thanks :-)

Thinking about it, I suppose that including these new modelines would not really make sense if the files are not reformatted according to these modelines at the same time. This is easily done but means potentially a lot of changes everywhere (I don't know to which extent the current files have a different formatting)... I hope this won't be too difficult to merge. I'll try to do this today.

[ClementPernet]

@vneiger thanks for volunteering. I confirm that not only should themodelines be updated, but also the whole file should be

• untabified (M-X untabify in emacs)
• auto-indented (M-X indent-region in emacs) This is the 3 steps that I am routinely doing every time I touch a file which had a wrong indent-tab-mode or tab-width setting. I must confess that, by ignorance of the cryptic vi modelines, I never touch it besides replacing the 8 into 4's.

[vneiger]

Thank you for the suggestion (I will also remove the trailing whitespaces). I must confess that I know nothing either about these modelines (apart from a few parameters such as tabstop etc mentioned by @P1K above), but while using LinBox it just seemed that this modeline used in LinBox seems to work well.

[vneiger]

PS : for the record, in case this can help vim users to respect the style in the future: applying the modeline to the whole file in vim (including untabifying and auto-indenting) amounts to pressing gg=G . Removing the trailing spaces is a bit less straightforward, but can be done by a single keystroke (e.g. F5) after putting the right thing in vim's config file (see e.g. https://vi.stackexchange.com/a/2285 ).

[bgrenet]

For trailing spaces in vim, simple keystroke is :%s/ *$// in command mode.

[romainlebreton]

Instead of

// Local Variables: // mode: C++ // tab-width: 4 // indent-tabs-mode: nil // c-basic-offset: 4 // End:

A one liner for this would best /* -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

Don't forget to process also the .inl files please :-)

[ClementPernet]

fixed in #209