mpdolce - LilyPond

Chapter 3: Fundamental concepts 61
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 a 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 Section 3.2.3 [Voices and vocals], page 52.
See also
Notation Reference: Section “Creating contexts” in Notation Reference.
3.3.3 Engravers explained
Every mark on the printed output of a score produced by LilyPond is produced by an Engraver.
Thus there is an engraver to print staves, one to print note heads, one for stems, one for beams,
etc, etc. In total there are over 120 such engravers! Fortunately, for most scores it is not
necessary to know about more than a few, and for simple scores you do not need to know about
any.
Engravers live and operate in Contexts. Engravers such as the Metronome_mark_engraver,
whose action and output apply to the score as a whole, operate in the highest level context –
the Score context.
The Clef_engraver and Key_engraver are to be found in every Staff Context, as different
staves may require different clefs and keys.
The Note_heads_engraver and Stem_engraver live in every Voice context, the lowest level
context of all.
Each engraver processes the particular objects associated with its function, and maintains
the properties that relate to that function. These properties, like the properties associated with
contexts, may be modified to change the operation of the engraver or the appearance of those
elements in the printed score.
Engravers all have compound names formed from words which describe their function. Just
the first word is capitalized, and the remainder are joined to it with underscores. Thus the
Staff_symbol_engraver is responsible for creating the lines of the staff, the Clef_engraver
determines and sets the pitch reference point on the staff by drawing a clef symbol.
Here are some of the most common engravers together with their function. You will see it is
usually easy to guess the function from the name, or vice versa.
Engraver Function
Accidental engraver Makes accidentals, cautionary and suggested accidentals
Beam engraver Engraves beams
Clef engraver Engraves clefs
Completion heads engraver Splits notes which cross bar lines
New dynamic engraver Creates hairpins and dynamic texts
Forbid line break engraver Prevents line breaks if a musical element is still active
Key engraver Creates the key signature
Metronome mark engraver Engraves metronome marking
Note heads engraver Engraves note heads