Re: GOP-PROP 5: build system output (probable 2?)

[Reinhold Kainhofer]

Am Freitag, 29. Juli 2011, 18:05:40 schrieben Sie:
> ----- Original Message -----
> From: "Reinhold Kainhofer" <address@hidden>
> > However, I have failed and still fail to see where the lilypond internals
> > printed with --verbose can be helpful in any way during the docs build.
> > Those
> > verbose debug messages are useful for debugging a lilypond bug. However,
> > in
> > the docs build, we are not interested in how lilypond works internally,
> > but
> > rather where a doc build fails due to bad input in a .ly or .tely file.
> 
> Well, I clearly agree.  However, just pushing the output to log files
> effectively does the same thing.

I don't think so. You don't easily get the error / warning messages printed 
directly on the console without wading through the log files. Having the 
important output (and only the important output) directly at the console 
speeds up debugging immensely.


> > The loglevel would then be set as 'lilypond --log=WARN file.ly', with
> > PROGRESS
> > (or INFO) being the default, i.e. no change to the current output.
> 
> Think this risks over-gilding the lily, TBH.  Personally, I've never used
> verbose.  We already have an option to suppress output/direct to
> logfile -dgui.

I should mention that I'm now no longer talking about the lilypond build 
system, but as a lilypond user, who writes large orchestral / choir scores 
(sometimes 12 movements with 23 instruments, resulting in 23 instrumental 
scores, choir score, full score, piano reduction etc.). There, I'm 
encountering the same problems as the lilypond build system, though.

I also have not used --verbose at all. To the contrary, I often wished that I 
could suppress the progress messages and just get the warnings / errors.

I have my own makefiles that call lilypond on all score files. Now, 
unfortunately, each first prints out >300 "Interpreting music..." lines. So, 
when I simply want to look at which warnings each of the instrumental scores 
generated, I have to wade through thousands of lines, which usually don't fit 
in the output buffer of the console window any more.

If lilypond has an option to suppress all progress messages and print just the 
warnings and errors, that would make my life as a music publisher much easier. 
That's my real intention here.

Redirecting all output to a log file only moves the problem to wading through 
a logfile, which is cluttered with progress messages.

I should also mention that internally in the code we already distinguish 
error, warning, progress and debug messages (ly:error, ly:warning, 
ly:progress, etc.). The only thing that is missing is a command-line option to 
let the user choose which of those (s)he wants to see.

Such a patch is pretty straightforward and a matter of hours.

Of course, that no longer belongs here in the GOP-PROP 5 (build system 
output), but is a general feature request for lilypond. The build system could 
then use it, but that's a different matter.

> > Since we print all messages to stderr, there is no way to filter the
> > output,
> > so we need to add a command line option to lilypond to prevent printing
> > undesired output in the first place (e.g. I have makefiles that call
> > lilypond
> > on several different huge files; there I'm not interested in the progress
> > messages, just in the warnings and error messages. The --log=... option
> > would
> > allow exactly this).
> 
> I remain of the view that this is wrong, and at some point there's likely
> to be a GOP discussion.  FWIW make sends progress to stdout and error to
> stderr...

Hehe, but lilypond prints everything to stderr, so all progress will end up in 
stderr, even when lilypond is run through make...

Cheers,
Reinhold
-- 
------------------------------------------------------------------
Reinhold Kainhofer, address@hidden, http://reinhold.kainhofer.com/
 * Financial & Actuarial Math., Vienna Univ. of Technology, Austria
 * http://www.fam.tuwien.ac.at/, DVR: 0005886
 * LilyPond, Music typesetting, http://www.lilypond.org