User-defined messages in .ly compilation output?

[Magnus Lewis-Smith]

Is it possible to write messages to the terminal during the compilation of a
.ly file?  (not the compilation of lilypond itself!)

For example, perhaps I would like to be able to indicate that the warnings
generated by a certain piece of code are to be expected, as in:

\version "2.2.2"
guitarPart = \notes {
  \key d \major
  d1 
  \key a \major
  a1
}
\score {
  \notes {
    <<
      \new Staff {
        %% COMPILES OK
        \clef bass
        \guitarPart
      }
      \new TabStaff {
        %% EXPECT WARNINGS: Junking event: `KeyChangeEvent'
        \guitarPart
      }
    >>
  }
  \paper{}
}

Is there a way to insert into the compilation output something like:

lilypond (GNU LilyPond) 2.2.2
Running lilypond-bin...
Now processing `file.ly'
Parsing...
Interpreting music... 

message:  expect errors in TabStaff       <----------- CAN I DO THIS?

file.ly:2:14: warning: Junking event: `KeyChangeEvent':
  \key d \majo
              r

file.ly:4:14: warning: Junking event: `KeyChangeEvent':
  \key a \majo
              r
[3]
Preprocessing graphical objects... 



Thanks for your help.
Magnus Lewis-Smith



        
        
                
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