Question about dir-locals c-mode.

Question about dir-locals c-mode.

[Ergus]

Hi:

This is probably a basic question, but I don't find any reference.

I have a .dir-locals.el file a bit long because the project implied is a
bit special regarding indentation. The problem is that the project is
either C and C++ code and the indentation in both cases is retty much
the same; but other files like python, bash or makefiles require
different indentation.

I am wondering if it is possible in the dir-locals to set a
configuration either for C and C++ without repeating myself.

Up to now I have:

(c++-mode . (...Long...))
(c-mode . (...Long...))

But everytime I update the C config I have to copy and paste in the
other...

is it possible to do something equivalent to:

((or c-mode c++-mode) . (...Long...))

Thanks in advance,
Ergus

Re: Question about dir-locals c-mode.

[Jean Louis]

* Ergus <spacibba@aol.com> [2020-11-08 02:52]:
> Hi:
> 
> This is probably a basic question, but I don't find any reference.
> 
> I have a .dir-locals.el file a bit long because the project implied is a
> bit special regarding indentation. The problem is that the project is
> either C and C++ code and the indentation in both cases is retty much
> the same; but other files like python, bash or makefiles require
> different indentation.

Did you try with local file variables?

M-x add-file-local-variable

Re: Question about dir-locals c-mode.

[Daniel Martín]

Ergus <spacibba@aol.com> writes:

> Hi:
>
> This is probably a basic question, but I don't find any reference.
>
> I have a .dir-locals.el file a bit long because the project implied is a
> bit special regarding indentation. The problem is that the project is
> either C and C++ code and the indentation in both cases is retty much
> the same; but other files like python, bash or makefiles require
> different indentation.
>
> I am wondering if it is possible in the dir-locals to set a
> configuration either for C and C++ without repeating myself.
>
> Up to now I have:
>
> (c++-mode . (...Long...))
> (c-mode . (...Long...))
>
> But everytime I update the C config I have to copy and paste in the
> other...
>
> is it possible to do something equivalent to:
>
> ((or c-mode c++-mode) . (...Long...))
>
> Thanks in advance,
> Ergus

There's no special syntax to match several major modes in
.dir-locals.el.  One alternative is to put your C and C++ configuration
under prog-mode and add specific entries for Python, Bash and Makefiles
modes.

Another alternative may be to use the "eval" variable to call a common
function that sets the file-local variables. Something like:

((c++-mode . ((eval . (apply-common-c-configuration))))
 (c-mode . ((eval . (apply-common-c-configuration)))))

Re: Question about dir-locals c-mode.

[Stefan Monnier]

> Up to now I have:
>
> (c++-mode . (...Long...))
> (c-mode . (...Long...))

FWIW, I had sent a patch to CC-mode to introduce a parent mode shared by
c-mode, c++-mode, and objc-mode, but Alan didn't like the idea.


        Stefan

Re: Question about dir-locals c-mode.

[Ergus]

On Sun, Nov 08, 2020 at 09:50:38AM -0500, Stefan Monnier wrote:
>> Up to now I have:
>>
>> (c++-mode . (...Long...))
>> (c-mode . (...Long...))
>
>FWIW, I had sent a patch to CC-mode to introduce a parent mode shared by
>c-mode, c++-mode, and objc-mode, but Alan didn't like the idea.
>
>
>        Stefan
:( There is the c-mode-common-hook I was actually expecting that there
should be something like c-mode-common. Somehow it seems intuitive for
me. Some packages like irony have actually some hacks to go around this
too.

Re: Question about dir-locals c-mode.

[Stefan Monnier]

>>> (c++-mode . (...Long...))
>>> (c-mode . (...Long...))
>>FWIW, I had sent a patch to CC-mode to introduce a parent mode shared by
>>c-mode, c++-mode, and objc-mode, but Alan didn't like the idea.
> :( There is the c-mode-common-hook I was actually expecting that there
> should be something like c-mode-common. Somehow it seems intuitive for
> me. Some packages like irony have actually some hacks to go around this
> too.

Note that `c-mode-common-hook` is not just common to C-like languages
but applies to all modes using the CC-mode framework, which includes
java-mode, awk-mode, php-mode, sieve-mode, and various others.  So it
risks being "too common" for the kind of usage you describe (and yes, my
patch had two parent modes: one common to C, C++, and ObjC, and another
one on top common to all CC-mode derivatives).


        Stefan