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<a name="Void-functions"></a>
Next: <a rel="next" accesskey="n" href="Functions-without-arguments.de.html#Functions-without-arguments">Functions without arguments</a>,
Previous: <a rel="previous" accesskey="p" href="Mathematics-in-functions.de.html#Mathematics-in-functions">Mathematics in functions</a>,
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<h4 class="subsection">6.1.5 Void functions</h4>
<p>A music function must return a music expression, but sometimes we
may want to have a function which does not involve music (such as
turning off Point and Click). To do this, we return a <code>void</code>
music expression.
<p>That is why the form
that is returned is the <code>(make-music ...)</code>. With the
<code>'void</code> property set to <code>#t</code>, the parser is told to
actually disregard this returned music
expression. Thus the important part of the void music function is the
processing done by the function, not the music expression that is
returned.
<pre class="example">noPointAndClick =
#(define-music-function (parser location) ()
(ly:set-option 'point-and-click #f)
(make-music 'SequentialMusic 'void #t))
...
\noPointAndClick % disable point and click
</pre>
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