Music function problem

[Peter Gentry]

I am trying to write an include file that will modify a music object dependent on the specified instrument.

 

I am trying to write a function that will call the current music object and a user supplied argument string/number with the object of modifying the music object depending on the supplied number/string.

 

I can get this to work if the two arguments are ( ly:music? color?) but not if they are (ly:music? number?) or (ly:music? string?)

 

The function call in an include file aimed to get a music object and a user number is 

 

callmyfunction =

#(define-music-function (parser location m n) (ly:music? number?)

(anotherfunction m n))

 

This is a fragment of the include file

 

In the lilypond file

...

\callmyfunction #2

....etc

The define-music-function does not accept a number or string my puzzle is how do I get the music object and the user argument into my include function. Any pointers gratefully recieved....

I think I am missing something crucial about define-music-function

regards
Peter Gentry