Re: file variables and man pages with preprocessors

[Werner LEMBERG <wl@gnu.org>]

>     Well, preconv acts as a filter -- as do (almost) all components
>     in groff -- thus reading something from the `end of a file' (a)
>     needs a temporary buffer since the input data stream is `stdin'
>     in most cases and (b) isn't implemented in preconv due to (a).
> 
> I don't understand this.  What is preconv, and what does it have to
> do with visiting these files in Emacs?

`preconv' is a new preprocessor (currently in the CVS of groff only)
which converts man pages in any input encoding to something groff can
digest.  It supports the GNU Emacs convention for coding tags at the
beginning of a file but not at the end of a file for the reasons given
above.

Consider this example of troff.man (omitting some lines for brevity):

  '\" t
  .ig
    troff.man
    Copyright (C) ...
  ..
  .
  .TH TROFF 1 "2000-10-20" "Groff Version 1.2.3"
  .SH NAME
  troff \- the troff processor of the groff text formatting system

Here, the first line indicates that the `tbl' preprocessor is needed;
and the `man' program will call it due to this line.

Now assume that I want to have this man page in, say, German.  It how
has to start with

  '\" t
  .\" -*- coding: latin-1 -*-
  .ig
    troff.man
    Copyright (C) ...
  ..
  .
  .TH TROFF 1 "2000-10-20" "Groff Version 1.2.3"
  .SH NAME
  troff \- Der troff-Prozessor des groff-Textformatierungssystems

to use latin-1 (or another suitable encoding like utf-8).

Opening such a file currently in Emacs doesn't select the proper file
encoding.


    Werner