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<a name="Saving-typing-with-variables-and-functions"></a>
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<h4 class="subsection">5.1.4 Saving typing with variables and functions</h4>
<p><a name="index-variables-442"></a><a name="index-variables-443"></a>
By this point, you've seen this kind of thing:
<blockquote>
<pre class="verbatim">
hornNotes = \relative c'' { c4 b dis c }
\score {
{
\hornNotes
}
}
</pre>
<p>
<a href="../8a/lily-718d27d0.ly">
<img align="middle"
border="0" src="../8a/lily-718d27d0.png" alt="[image of music]">
</a>
</p>
</blockquote>
<p>You may even realize that this could be useful in minimalist music:
<blockquote>
<pre class="verbatim">
fragmentA = \relative c'' { a4 a8. b16 }
fragmentB = \relative c'' { a8. gis16 ees4 }
violin = \new Staff { \fragmentA \fragmentA \fragmentB \fragmentA }
\score {
{
\violin
}
}
</pre>
<p>
<a href="../3b/lily-928ad868.ly">
<img align="middle"
border="0" src="../3b/lily-928ad868.png" alt="[image of music]">
</a>
</p>
</blockquote>
<p>However, you can also use these variables (also known as
variables, macros, or (user-defined) command) for tweaks:
<blockquote>
<pre class="verbatim">
dolce = \markup{ \italic \bold dolce }
padText = { \once \override TextScript #'padding = #5.0 }
fthenp=_\markup{ \dynamic f \italic \small { 2nd } \hspace #0.1 \dynamic p }
violin = \relative c'' {
\repeat volta 2 {
c4._\dolce b8 a8 g a b |
\padText
c4.^"hi there!" d8 e' f g d |
c,4.\fthenp b8 c4 c-. |
}
}
\score {
{
\violin
}
\layout{ragged-right=##t}
}
</pre>
<p>
<a href="../fb/lily-ace13d5f.ly">
<img align="middle"
border="0" src="../fb/lily-ace13d5f.png" alt="[image of music]">
</a>
</p>
</blockquote>
<p>These variables are obviously useful for saving
typing. But they're worth considering even if you
only use them once – they reduce complexity. Let's
look at the previous example without any
variables. It's a lot harder to read, especially
the last line.
<pre class="example">violin = \relative c'' {
\repeat volta 2 {
c4._\markup{ \italic \bold dolce } b8 a8 g a b |
\once \override TextScript #'padding = #5.0
c4.^"hi there!" d8 e' f g d |
c,4.\markup{ \dynamic f \italic \small { 2nd }
\hspace #0.1 \dynamic p } b8 c4 c-. |
}
}
</pre>
<!-- TODO Replace the following with a better example -td -->
<!-- Skylining handles this correctly without padText -->
<p>So far we've seen static substitution – when LilyPond
sees <code>\padText</code>, it replaces it with the stuff that
we've defined it to be (ie the stuff to the right of
<code>padtext=</code>).
<p>LilyPond can handle non-static substitution, too (you
can think of these as functions).
<blockquote>
<pre class="verbatim">
padText =
#(define-music-function (parser location padding) (number?)
#{
\once \override TextScript #'padding = #$padding
#})
\relative c''' {
c4^"piu mosso" b a b
\padText #1.8
c4^"piu mosso" d e f
\padText #2.6
c4^"piu mosso" fis a g
}
</pre>
<p>
<a href="../fd/lily-5fb6bbf8.ly">
<img align="middle"
border="0" src="../fd/lily-5fb6bbf8.png" alt="[image of music]">
</a>
</p>
</blockquote>
<p>Using variables is also a good way to reduce work if the
LilyPond input syntax changes (see <a href="Updating-old-input-files.html#Updating-old-input-files">Updating old input files</a>). If
you have a single definition (such as <code>\dolce</code>) for all your
input files (see <a href="Style-sheets.html#Style-sheets">Style sheets</a>), then if the syntax changes, you
only need to update your single <code>\dolce</code> definition,
instead of making changes throughout every <code>.ly</code> file.
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