Re: Please do not deprecate perl-mode in favour of cperl-mode

[Stefan Kangas]

"Paul W. Rankin" via "Emacs development discussions."
<emacs-devel@gnu.org> writes:

> On 2023-12-03 23:20, Harald Jörg wrote:
>
>> CPerl mode has several predefined indentation styles, a recent addition
>> is to indent according to Damian Conway's "Perl Best Practices".  This
>> can be activated with (cperl-set-style "PBP").  It _should_ be the
>> default these days, but it isn't for compatibility reasons.  in PBP
>> style, indentation is like this:
>>
>>     $r->get(
>>         '/test'
>>     );

BTW, how bad are the above mentioned compatibility concerns?  If they
are minor, perhaps we could change to the modern PBP style?

AFAIK, the PBP book was released around 20 years ago, and it's style was
pretty widely adopted by the Perl community from what I could tell at
the time.  It's been a long time since I last coded Perl seriously
though, so I'm very much out of the loop.

> Ah this is excellent. "PBP" is indeed how I assume Perl should be
> indented. But how do I set this as a user option, i.e. M-x
> customize-option? I think M-x cperl-set-style is not easily discoverable
> (i.e. I didn't find it). For my own packages I encourage user discovery
> through M-x customize-group, but I think here cperl-set-style would
> remain elusive...

I think this is one example of CPerl mode being different from typical
Emacs conventions.  I think we should introduce a new defcustom with the
same name so that this can be set from `M-x customize`.

> Still on indentation, the main way CPerl Mode bumps me out of things is
> that it doesn't indent the current region (like other programming
> modes), only the current line. If CPerl Mode would indent the region on
> TAB with "PBP" that would go a long way to making it feel more
> approachable.

Yet another case of CPerl mode being weird, and this one sounds a lot to
me like a plain bug.  Note that CPerl mode has several commands,
including a separate one to indent the region, for some reason.

Could you report this one as a bug so that we can discuss in more detail
what, if anything, could be done about this?

> Cool. In general where CPerl mode departs from convention I think it
> would be greatly appreciated to have an option to reign it back in ;)

I think we need to consider every case of that individually, so please
do report bugs.

> Something that may warrant a separate bug report is CPerl Mode's
> departure from the use of font-lock-* faces in a few key faces. The big
> advantage of sticking with the font-lock-* faces is that a user can more
> or less define their own theme just by customizing these faces. The
> faces in question are:
>
> cperl-array-face
> cperl-hash-face
> cperl-nonoverridable-face
>
> Each of which I think could benefit from instead inheriting from a
> font-lock-* face by default, to make things look a little more
> aesthetically pleasing. That said, I don't know which font-lock-* face
> is most appropriate, maybe combinations e.g.
> font-lock-variable-name-face plus bold plus underline.

This one warrants a bug report too, yes.