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Re: Auto Fill Comments

From: tomas
Subject: Re: Auto Fill Comments
Date: Thu, 26 Nov 2020 19:27:34 +0100
User-agent: Mutt/1.5.21 (2010-09-15)

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.

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

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.


[1] Online here:
    For the user:
    For the lisp programmer:

    although you /should/ have those manuals with your Emacs installation.
    This is preferrable, since they should correspond to your Emacs


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