Re: Auto Fill Comments

[Christopher Dimech <dimech@gmx.com>]

> Sent: Thursday, November 26, 2020 at 7:27 PM
> From: tomas@tuxteam.de
> To: "Christopher Dimech" <dimech@gmx.com>
> Cc: help-gnu-emacs@gnu.org
> Subject: Re: Auto Fill Comments
>
> On Thu, Nov 26, 2020 at 06:22:26PM +0100, Christopher Dimech wrote:
>
> [...]
>
> > Does that mean that setq-default also enables automatic filling?
> >
> > I need some explanation about setq, setq-default, and set-local.
>
> You should skim the manual's "Variables" section [1]
>
> In a nutshell, variables are a way to attach a value to a
> name. In Emacs, there are different kinds of variables.
> For our current purposes, we consider global variables
> and buffer-local variables (there are more!).
>
> A global variable is seen from everywhere. If you set its
> value while in buffer A, this change will be seen in every
> other buffer.
>
> Buffer-local variables can have one value per-buffer. It
> shadows the global variable (if there's any with the same
> name). Most mode things are buffer local. The `fill-column'
> is one example. You might want different values for it
> in different buffers (say, you're editing two sources with
> different styles in one session), that's why it is set up
> as a buffer-local variable.
>
> So if you do (setq fill-column 72) in the context of buffer
> A, only buffer A gets to see that.

Had thought that setq was actually a global thing, not local.
For local variables I was using "let" and "let*", but that seems
a wrong understanding.


> Setq-local (not set-local, as you wrote) is just a convenience,
> which makes the named variables buffer-local and sets their
> values (thus leaving possibly like-named global variables
> alone).
>
> The setq-default is for setting one or more buffer-local
> variables's default values.
>
> The gory details are in the Elisp manual [3]. There's also
> an explanation for setq-default which is much better than
> I could come up with here.
>
> Cheers
>
> [1] Online here:
>     For the user:
>     https://www.gnu.org/software/emacs/manual/html_node/emacs/Variables.html#Variables
>     For the lisp programmer:
>     https://www.gnu.org/software/emacs/manual/html_node/elisp/Variables.html#Variables
>
>     although you /should/ have those manuals with your Emacs installation.
>     This is preferrable, since they should correspond to your Emacs
>     version.
>
> [2] https://www.gnu.org/software/emacs/manual/html_node/elisp/Buffer_002dLocal-Variables.html#Buffer_002dLocal-Variables
>