LilyPond Beginnershandleiding

Hoofdstuk 3: Fundamentele concepten 60
The input is rather sparse, but in the output, bar lines, accidentals, clef, and time signature
have been added. When LilyPond interprets the input the musical information is parsed from left
to right, similar to the way a performer reads the score. While reading the input, the program
remembers where measure boundaries are, and which pitches require explicit accidentals. This
information must be held on several levels. For example, an accidental affects only a single staff,
while a bar line must be synchronized across the entire score.
Within LilyPond, these rules and bits of information are grouped in Contexts. We have
already introduced the Voice context. Others are the Staff and Score contexts. Contexts are
hierarchical to reflect the hierarchical nature of a musical score. For example: a Staff context
can contain many Voice contexts, and a Score context can contain many Staff contexts.
Each context has the responsibility for enforcing some notation rules, creating some notation
objects and maintaining the associated properties. For example, the Voice context may introduce
an accidental and then the Staff context maintains the rule to show or suppress the accidental
for the remainder of the measure.
As another example, the synchronization of bar lines is, by default, handled in the Score
context. However, in some music we may not want the bar lines to be synchronized – consider a
polymetric score in 4/4 and 3/4 time. In such cases, we must modify the default settings of the
Score and Staff contexts.
For very simple scores, contexts are created implicitly, and you need not be aware of them.
For larger pieces, such as anything with more than one staff, they must be created explicitly
to make sure that you get as many staves as you need, and that they are in the correct order.
For typesetting pieces with specialized notation, it is usual to modify existing, or even to define
totally new, contexts.
In addition to the Score, Staff and Voice contexts there are contexts which fit between the
score and staff levels to control staff groups, such as the PianoStaff and ChoirStaff contexts.
There are also alternative staff and voice contexts, and contexts for lyrics, percussion, fret boards,
figured bass, etc.
The names of all context types are formed from one or more words, each word being capitalized
and joined immediately to the preceding word with no hyphen or underscore, e.g.,
GregorianTranscriptionStaff.
Zie ook
Notation Reference: Sectie “Contexts explained” in Notatie-handleiding.
3.3.2 Creating contexts
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