\version "2.15.38"


\relative c' {
  c4 d e\< f g f\> e f g1\!
}

% Definition of \layout block in variable
% overrides a property
layoutVariable = \layout {
  \context {
    \Score
    \override Hairpin #'style = #'dashed-line
  }
}

% \first \layout block overrides one property
\layout {
  \context {
    \Score
    \override Hairpin #'color = #magenta
  }
}



% second \layout block overrides a second property
% Effects are merged
\layout {
  \context {
    \Score
    \override Hairpin #'thickness = 3
    %\override Hairpin #'style = #'dashed-line
  }
}


% Uncomment the following line to see that the third \layout block
% isn't merged but hides the other ones
\layout { \layoutVariable }

% move the variable definition and the call of \layoutVariable
% around to see that all \context blocks between the definition
% and the calling of this \layout block are ignored.