Re: RS/RE and paragraphing macros

[Alex Colomar]

Hi Branden,

On 2/20/23 07:10, G. Branden Robinson wrote:
[...]

> > Okay, so now it makes sense.  There's indentation and left margin, and
> > they're different things (still weird that the amount of movement(?)
> > of the left margin is also called indentation (.RS [indentation])).
>
> That's such a good point that I pushed a fix for it.
>
> https://git.savannah.gnu.org/cgit/groff.git/commit/?id=b14a7dda59bf0fcf10667a40a31fabe78e479ebd

:)

> > But I still have some doubts:
> >
> > Is RS a paragraphing macro?
>
> No.  It breaks the line and moves the margin.

Ahh, okay, so it breaks the line but it doesn't separate paragraphs.

> > Does it start a new "normal" paragraph?
>
> Yes and no?  I suspect you are thinking of paragraph macros as things
> that have scope.  Or of things like HTML elements that open <tag> and
> close </tag>.

Not really.  I don't know much HTML

[...]
> > Or does it continue in the same paragraph?  Empirically, I'd say it
> > starts a new paragraph, but that seems undocumented.
>
> Paragraphing macros in *roff packages _separate_ paragraphs; they do not
> _enclose_ paragraphs.

Okay, so RS doesn't separate paragraphs.  It does only break a line and 
move the left margin.  Where do you end up after breaking a line?  Since 
you didn't start a new paragraph, I'd guess that it would be reasonable 
to end up at the same indentation as the previous paragraph, no?  Let's 
see with an example what we get:


$ cat br.man
.TH a s d f
.SH br
foo bar baz
.IP
qwe rty uio
.br
zxc vbn xcv
.PP
lkjhjhjg hgfgfd
$ man ./br.man | cat
a(s)                                                              a(s)

br
       foo bar baz

              qwe rty uio
              zxc vbn xcv

       lkjhjhjg hgfgfd

f                                  d                              a(s)



Okay, this is what I expected.  .br continues at the same indentation of 
the IP, just at the next line.  Let's try the same with RS/RE; I'll use 
an inset of 0, to don't move the margin, so we only break the line.


$ cat RS.man
.TH a s d f
.SH br
foo bar baz
.IP
qwe rty uio
.RS 0
zxc vbn xcv
.RE
.PP
lkjhjhjg hgfgfd
alx@dell7760:~/tmp$ man ./RS.man | cat
a(s)                                                              a(s)

br
       foo bar baz

              qwe rty uio
       zxc vbn xcv

       lkjhjhjg hgfgfd

f                                  d                              a(s)



Hummm, this is definitely not as simple as "breaks the line and moves 
the margin".  The margin is not moved because of 0, so this should be 
just equivalent to .br from your own definition.  However, it's not.  It 
does some extra magic, which I'd call "RS sets the indentation of the 
scoped block to 0; RE resets to the previous indentation".

I'm not saying that is necessarily bad, but we need to document it.  In 
fact, after thinking about it, it can help to start a new block of 
indentation: that way, when you close with RE, you'll be able to 
continue bullet lists without specifying the indentation, even if some 
bullet within the list was rather long and had nested stuff.

So, I think RS/RE has the right choice; but it needs some more 
documentation.

Did that make sense to you?

Cheers,

Alex

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