What is the use of "categories"?

What is the use of "categories"?

[Marcin Borkowski]

Hi all,

I found out about "categories" today - see (info "(elisp) Categories").
What is the use of them?  I noticed that filling functions use them
(which makes sense), is there anything else in stock Emacs or packages
that does?

TIA,

--
Marcin Borkowski
http://mbork.pl

Re: What is the use of "categories"?

[Eli Zaretskii]

> From: Marcin Borkowski <mbork@mbork.pl>
> Date: Sun, 26 Aug 2018 08:30:59 +0200
> 
> I found out about "categories" today - see (info "(elisp) Categories").
> What is the use of them?  I noticed that filling functions use them
> (which makes sense), is there anything else in stock Emacs or packages
> that does?

You can use categories in regular expressions, via the \c escape.
This could allow you, for example, to find Katakana characters, or
characters that are consonants.

Re: What is the use of "categories"?

[Marcin Borkowski]

On 2018-08-26, at 16:25, Eli Zaretskii <eliz@gnu.org> wrote:

>> From: Marcin Borkowski <mbork@mbork.pl>
>> Date: Sun, 26 Aug 2018 08:30:59 +0200
>> 
>> I found out about "categories" today - see (info "(elisp) Categories").
>> What is the use of them?  I noticed that filling functions use them
>> (which makes sense), is there anything else in stock Emacs or packages
>> that does?
>
> You can use categories in regular expressions, via the \c escape.
> This could allow you, for example, to find Katakana characters, or
> characters that are consonants.

Thanks!

-- 
Marcin Borkowski
http://mbork.pl

Re: What is the use of "categories"?

[John Shahid]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Marcin Borkowski <mbork@mbork.pl>
>> Date: Sun, 26 Aug 2018 08:30:59 +0200
>> 
>> I found out about "categories" today - see (info "(elisp) Categories").
>> What is the use of them?  I noticed that filling functions use them
>> (which makes sense), is there anything else in stock Emacs or packages
>> that does?
>
> You can use categories in regular expressions, via the \c escape.
> This could allow you, for example, to find Katakana characters, or
> characters that are consonants.

Should the Elisp manual be updated to link to `Emacs (Regexp Backslack)' ?

Re: What is the use of "categories"?

[Eli Zaretskii]

> From: John Shahid <jvshahid@gmail.com>
> Cc: help-gnu-emacs@gnu.org
> Date: Wed, 29 Aug 2018 22:47:02 -0400
> 
> > You can use categories in regular expressions, via the \c escape.
> > This could allow you, for example, to find Katakana characters, or
> > characters that are consonants.
> 
> Should the Elisp manual be updated to link to `Emacs (Regexp Backslack)' ?

It should be the other way around, and that link already exists.