Re: understanding fill-region, paragraph-separate, and paragraph-start

[Stephen Berman]

On Tue, 11 Dec 2018 13:47:01 -0800 Eric Abrahamsen <eric@ericabrahamsen.net> 
wrote:

> In EBDB I've been using a manual function to correctly format record
> fields. Briefly, the output looks just like BBDB:
>
> John Doe
>    mail: email1@address.com, email2@address.com, email3@address.com
>   notes: This is John Doe, a guy I met in blah blah blah blah blah
>
> In narrow windows, I want the above two lines to fill/wrap like so:
>
> John Doe
>    mail: email1@address.com, email2@address.com,
>          email3@address.com
>   notes: This is John Doe, a guy I met in blah blah
>          blah blah blah
>
> So each line has an overhanging label, and subsequent lines are filled
> to the beginning of the text on the first line.
>
> Right now this is done "manually" with a function that just goes in and
> sticks in spaces.
>
> In the interest of Doing the Right Thing (and learning how filling
> works), I'm trying to accomplish the same thing by setting the correct
> values of `fill-column', `paragraph-separate', and `paragraph-start',
> and then calling `fill-region' on all the lines at once.
>
> I haven't been able to get this right. I think the regexp I want is
> "[^:]+: ", meaning a paragraph starts with some stuff that's not a
> colon, then a colon and a space. But if I use that as the value of
> `paragraph-start', nothing happens (the lines still look like example
> one above), if I use it as the value of `paragraph-separate' the region
> is turned into a single line (but wrapped to `fill-column'), and if I
> use it as the value of both the region is turned into a single long line
> that isn't filled.
>
> I'll worry about the underhang later -- how is this meant to work? I
> also thought `paragraph-separate' might be a "\n", but that goes back to
> doing nothing.
>
> And hints much appreciated!

I can't help with paragraph-separate, fill-region etc., but FWIW you can
get the visual effect of the above by using a combination of
visual-line-mode and wrap-prefix.

Steve Berman