\version "2.13.1"
#(ly:set-option 'point-and-click #f)

% Some sample text dynamic spanners, to be used as postfix operators
crxxx = #(make-music 'CrescendoEvent 'span-direction START 'crescendoSpanner 'text 'crescendoText "cresc.")
crpoco = #(make-music 'CrescendoEvent 'span-direction START 'crescendoSpanner 'text 'crescendoText "cresc. poco a poco")
dimxxx = #(make-music 'DecrescendoEvent 'span-direction START 'decrescendoSpanner 'text 'decrescendoText "dim.")

\relative c' { c4\crxxx d4 e4 f4 |
  g4 a4\! b4\crpoco c4 |
  c4 d4 e4 f4 |
  g4 a4\! b4\< c4 |
  g4\dimxxx a4\< b4\crxxx c4\!
}



% Two functions for (de)crescendo spanners where you can explicitly give the 
% spanner text.
mycresc = #(define-music-function (parser location mymarkup) (string?)
  (make-music 'CrescendoEvent 'span-direction START 'crescendoSpanner 'text 'crescendoText mymarkup)
)
mydecresc = #(define-music-function (parser location mymarkup) (string?)
  (make-music 'DecrescendoEvent 'span-direction START 'decrescendoSpanner 'text 'decrescendoText mymarkup)
)

\relative c' { c4\mycresc "blah.." c4 c4 c4 |
  c4\mydecresc "...halb" c4 c4 c4 |
  c4 c4\! c4 c4 }