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Date: Fri, 13 Oct 2023 12:13:49 +0200
From: Ingo Schwarze <schwarze@usta.de>
To: Baptiste Daroussin <bapt@freebsd.org>
Cc: tech@mandoc.bsd.lv
Subject: Re: Naive patch for handling empty input
Message-ID: <ZSkYXX2PdK0JnCKw@asta-kit.de>
References: <ncotcm65ah3e2q64b5cejjk74oc2c26uueqns435r4cdolsusr@aecbtptwad72>
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In-Reply-To: <ncotcm65ah3e2q64b5cejjk74oc2c26uueqns435r4cdolsusr@aecbtptwad72>

Hi Bapt,

Baptiste Daroussin wrote on Fri, Oct 13, 2023 at 09:30:18AM +0200:

> Please find attached a naive patch to handle dealing with empty

Why would you want to do anything like that?

While empty input is valid low-level roff(7) input, it is not a valid
manual page.   While mandoc(1) wants to be compatible with groff
in manual pages, it is not a goal to be compatible with respect to
each and every low-level roff(7) feature outside of manual pages.

> This is probably a two naive approach, but I didn't want to come
> with empty hands :D
> 
> the issue is the following:
> ./mandoc </dev/null
> 
> before the patch is show 3 lines
> after nothing

I guess which approach makes sense for empty input depends on the
reasons *why* you want to handle empty input in any particular way.
So far, i cannot think of any possible reasons.

Also, where do you want to stop?

Do you want the output of

  echo foo | mandoc

to become compatible with

  echo foo | groff -ket -ww -mtty-char -Tascii -P -c

If yes, your patch is indeed much too naive.
If not, what is so special about empty input compared to other
low-level roff(7) non-manual-page input?

Yours,
  Ingo
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