lilypond-learning: Creating contexts
3.3.2 Creating contexts
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In an input file a score block, introduced with a ‘\score’ command,
contains a single music expression and an associated output definition
(either a ‘\layout’ or a ‘\midi’ block). The ‘Score’ context is usually
left to be created automatically when the interpretation of that music
expression starts.
For scores with only one voice and one staff, the ‘Voice’ and ‘Staff’
contexts may also be left to be created automatically, but for more
complex scores it is necessary to create them by hand. The simplest
command that does this is ‘\new’. It is prepended to a music
expression, for example
\new TYPE MUSIC-EXPRESSION
where TYPE is a context name (like ‘Staff’ or ‘Voice’). This command
creates a new context, and starts interpreting the MUSIC-EXPRESSION
within that context.
Note: \‘new Score’ should not be used as the essential
top-level ‘Score’ context is created automatically when the
music expression within the \‘score’ block is interpreted.
Score-wide default values of context properties can be changed
properties::
You have seen many practical examples which created new ‘Staff’ and
‘Voice’ contexts in earlier sections, but to remind you how these
commands are used in practice, here’s an annotated real-music example:
\score { % start of single compound music expression
<< % start of simultaneous staves section
\time 2/4
\new Staff { % create RH staff
\clef "treble"
\key g \minor
\new Voice { % create voice for RH notes
\relative c'' { % start of RH notes
d4 ees16 c8. |
d4 ees16 c8. |
} % end of RH notes
} % end of RH voice
} % end of RH staff
\new Staff << % create LH staff; needs two simultaneous voices
\clef "bass"
\key g \minor
\new Voice { % create LH voice one
\voiceOne
\relative g { % start of LH voice one notes
g8 <bes d> ees, <g c> |
g8 <bes d> ees, <g c> |
} % end of LH voice one notes
} % end of LH voice one
\new Voice { % create LH voice two
\voiceTwo
\relative g { % start of LH voice two notes
g4 ees |
g4 ees |
} % end of LH voice two notes
} % end of LH voice two
>> % end of LH staff
>> % end of simultaneous staves section
} % end of single compound music expression
[image src="" alt="[image of music]" text="image of music" ]
(Note how all the statements which open a block with either a curly
bracket, ‘{’, or double angle brackets, ‘<<’, are indented by two
further spaces, and the corresponding closing bracket is indented by
exactly the same amount. While this is not required, following this
practice will greatly reduce the number of ‘unmatched bracket’ errors,
and is strongly recommended. It enables the structure of the music to
be seen at a glance, and any unmatched brackets will be obvious. Note
too how the LH staff is created using double angle brackets because it
requires two voices for its music, whereas the RH staff is created with
a single music expression surrounded by curly brackets because it
requires only one voice.)
The ‘\new’ command may also give an identifying name to the context
to distinguish it from other contexts of the same type,
\new TYPE = ID MUSIC-EXPRESSION
Note the distinction between the name of the context type, ‘Staff’,
‘Voice’, etc, and the identifying name of a particular instance of that
type, which can be any sequence of letters invented by the user. Digits
and spaces can also be used in the identifying name, but then it has to
be placed in quotes, i.e. ‘\new Staff = "MyStaff 1" MUSIC-EXPRESSION’.
The identifying name is used to refer back to that particular instance
of a context. We saw this in use in the section on lyrics, see 
Voices and vocals.
See also
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Notation Reference: (lilypond-notation)Creating and referencing
contexts.
Info Catalog
lilypond-learning: Contexts explained
lilypond-learning: Contexts and engravers
lilypond-learning: Engravers explained