Re: [Groff] Formatting algorithm

[Peter Schaffter]

On Wed, Apr 23, 2014, Ted Harding wrote:
> I think some confusion is possibly arising here. See in-line below.
>
> > Doesn't a paragraph logically conclude at any request which introduces a
> > break?  Or invocation of any macro which itself invokes such a request?
> >  (In addition to an empty input line, or one with leading white space,
> > which implies a break?)  All of these exhibit one common feature: the
> > introduction of the break.
> 
> I think I have to disagree here. For example, in the middle of a
> paragraph I may wish to put some text centred on lines by itself,
> and this may be in the middle of a sentence -- perhaps a parenthetical
> quotation. Or, in technical writing, a displayed equation in the
> middle of a sentence.

This was my original thinking, but I'm inclined to see things
Keith's way now.  The confusion you refer to arises from
terminology.  There are logical paragraphs, which may include lists,
equations, quotes, and whatever other material logically belongs to
the paragraph, and there are "formatting paragraphs", if I may coin
a phrase, which refer to chunks of text that need to be adjusted.

Any time you introduce a break, even within a logical paragraph, the
preceding text needs to be adjusted.  I can't see any advantage to
including the text after an in-paragraph insertion in the adjustment
process, except in the case of a paragraph that flows around the
insertion--your "middle of the sentence" scenario.  In such a
circumstance, your .br would, at any rate, have to be a .brp unless
the insertion switched to a new environment, most likely within a
diversion.  If that were the case, the formatting algorithm, which I
assume is environment-specific, would continue to gather text once
the new environment was popped, and format the entire chunk as a
single paragraph at the next occurence of a break.

If my thinking is clear on this, a break, by itself, would be
still be sufficient to indicate end-of-paragraph.

BTW--does anyone know how KP/TeX handles paragraphs with "spread"
(.brp) lines?
 
> [1] The current paragraph is in a diversion, and the start of the
> paragraph macro includes the closure of the preceding paragraph
> (if any) and referral of the (now closed) diversion to the "format
> paragraph as a whole" process.

I'm uneasy with the notion of re-writing paragraph macros so that
every paragraph is in a diversion.  It makes more sense to put
insertions in paragraphs into diversions, as described above--if
for no other reason that, in most cases, that's how they're already
handled.

-- 
Peter Schaffter
http://www.schaffter.ca