implicitly running a lilypond script through a python script before compilation

[Joseph Chrestien]

Hi all,

I know this is going to sound strange: is it possible (or even imaginable) to 
run a Python code snippet from "within" Lilypond code at compile time? 

This is my situation: I am currently using a custom extension of the "Column 
markup" Frescobaldi snippet, to print verses below a staff. So far, so good 
(just discovered these snippets - very nice indeed!), but I am compiling quite 
a large library I am afraid I might want to change some details in the snippet 
as time goes by. Currently, that would mean highlight-clicking every single ly 
file. 

I am interested if anybody has a clue in how I can tweak Lily configs (if 
possible) so that my input script (A) would be automatically submitted to (say) 
a Python script called `verse-markup` located in the right folder and would be 
*implicitly* transformed into script (B). [See below]

I had a vague idea I could change the Frescobaldi execute path so that the 
script (invisibly) first goes to Python before being submitted to Lilypond in 
the "script B" form - does that seem any good? Has anyone already done it, who 
could give me a tip?

Thanks!
Joseph


PS. or maybe a magic "\include pysnippets.ly" command ? that would be absolute 
dream :)

------------------------------------------
Script A: what I want in my script window
------------------------------------------
\score { \relative c'' { c2 g4 e c1 } }

%!%!%!snippet:verse-markup%!%!%!
This is my first verse
La la la la la

This is my second verse
Lo lo lo lo lo
%!%!%!end-snippet%!%!%!

------------------------------------------
Script B: what I want Lilypond to read at compile time and change to PDF
------------------------------------------
\score { \relative c'' { c2 g4 e c1 } }

\markup{
    \line { This is my first verse }
    \line { La la la la la }
    \line { This is my second verse }
    \line { Lo lo lo lo lo } 
    % I know this markup doesn't work but it made it simple ;-)
}

------------------------------------------
Snippet: something like this should be saved in a nearby folder
------------------------------------------
text = '\n'.join(r'\line { %s }' % l for l in text.splitlines())
if state[-1] != 'markup':
    text = '\\markup {\n%s\n}' % text