Re: How to get the total length of Sequential Music

[Hans Sommer]

David Nalesnik <david.nalesnik <at> gmail.com> writes:

> 
> Hi Hans,
> On Sun, Oct 12, 2014 at 4:38 AM, Hans Sommer <hansisommer <at> gmx.de>
wrote:Hello,
> I am relatively new to Lilypond.
> I try to check the total length of a SequentialMusic part, i.e.
> my_score_part = { c'4 d e f }
> I want to get the result 4 quarters (or any other numerical representation)
> and for
> my_score_part2 = { c'4 d e f g8}
> 
> 
> (This isn't a valid name for a variable, so I changed it below.)
>  
> 
> 
> should deliver 4 quarter and 1 eighth.
> I found in the documentation the property:
>  length-callback (procedure):
>     ly:music-sequence::cumulative-length-callback
> but I don't know how to use it.
> I would be very thankful, if anybody could provide an example.
> 
> 
> I'm not familiar with this property, but it's relatively easy to determine
the length of a music expression.  Try this:
> 
>  \version "2.19.10"
> 
> my_score_part = { c'4 d e f }
> 
> my_score_part_two = { c'4 d e f g8 }
> 
> #(display (ly:music-length my_score_part))
> 
> #(display (ly:music-length my_score_part_two))
> 
> Hope this is helpful,
> David
> 
> 
> 
> 
> 
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> 

Thank you David,

that was what I was looking for.

When I use
 #(display (ly:music-length my_score_part))
I get in the lilypond log file (depending on the score length) someting like
that:

#<Mom 2>

Is there a possibility to write the result in an extra text file  (I want to
process the result by a program, that is actually starting the lilypond
compilation. It should check the score length and eventually throw an error).
I guess some scheme routines will be necessary, but I did not work with
scheme in the past, so maybe somebody has a small example code.


Regards 

Hans