let us return to the first example and examine the @code{\score}
command, leaving the others to default.
-A @code{\score} block must always contain just one music
+A @code{\score} block must always contain just one music
expression, and
this must appear immediately after the @code{\score} command.
Remember that a music expression could be anything from a single
Since everything is inside @code{@{ ... @}}, it counts
as one music expression.
-As we saw previously, the @code{\score} block can contain other
+As we saw previously, the @code{\score} block can contain other
things, such as
@example
@end example
@noindent
-Some people put some of those commands outside the @code{\score}
-block -- for example, @code{\header} is often placed above the
-@code{\score} command. That's just another shorthand that LilyPond
-accepts.
+Note that these three commands -- @code{\header}, @code{\layout}
+and @code{\midi} -- are special: unlike all other commands which
+begin with a backward slash (@code{\}) they are @emph{not} music
+expressions and are not part of any music expression.
+So they may be placed inside a @code{\score} block
+or outside it. In fact, these commands are commonly placed
+outside the @code{\score} block -- for example, @code{\header}
+is often placed above the @code{\score} command because headers
+naturally appear at the top of a score. That's just another
+shorthand that LilyPond accepts.
Two more commands you have not previously seen are
@code{\layout @{ @}} and @code{\midi @{@}}. If these appear as
However, although this is an interesting and useful exercise to
help you to understand how sequential and simultaneous blocks work,
-in practice one would perhaps choose to code this as two
+in practice one would perhaps choose to code this as two
@code{\score} blocks within an implicit @code{\book} block, as
follows:
Contexts are responsible for holding the values of a number of
context @emph{properties}. Many of them can be changed to
influence the interpretation of the input and so change the
-appearance of the output. They are changed by the
+appearance of the output. They are changed by the
@code{\set} command. This takes the form
@example
an Integer is a positive whole number, a Real is a positive
or negative decimal number, and text is enclosed in double
apostrophes. Note the occurrence of hash signs,
-(@code{#}), in two different places -- as part of the Boolean
+(@code{#}), in two different places -- as part of the Boolean
value before the @code{t} or @code{f}, and before @emph{value}
-in the @code{\set} statement. So when a Boolean is being
-entered you need to code two hash signs, e.g., @code{##t}.
+in the @code{\set} statement. So when a Boolean is being
+entered you need to code two hash signs, e.g., @code{##t}.
Before we can set any of these properties we need to know
in which context they operate. Sometimes this is obvious,
}
\new Staff \relative c' {
\set instrumentName = #"Alto" % Wrong!
- d4 d
+ d4 d
}
>>
@end lilypond
Remember the default context name is Voice, so the second
@code{\set} command set the property @code{instrumentName} in the
Voice context to @qq{Alto}, but as LilyPond does not look
-for any such property in the @code{Voice} context, no
-further action took place. This is not an error, and no error
+for any such property in the @code{Voice} context, no
+further action took place. This is not an error, and no error
message is logged in the log file.
-Similarly, if the property name is mis-spelt no error message
+Similarly, if the property name is mis-spelt no error message
is produced, and clearly the expected action cannot be performed.
-If fact, you can set any (fictitious) @q{property} using any
-name you like in any context that exists by using the
+If fact, you can set any (fictitious) @q{property} using any
+name you like in any context that exists by using the
@code{\set} command. But if the name is not
known to LilyPond it will not cause any action to be taken.
This is one of the reasons why it is highly recommended to
>>
@end lilypond
-The value of every property set in this way can be reset
-to its original value with the @code{\unset} command.
-
+As another example, if @code{clefOctavation} is set in
+the @code{Score} context this immediately changes the value
+of the octavation in all current staves and sets a new default
+value which will be applied to all staves.
+
+The opposite command, @code{\unset}, effectively removes the
+property from the context, which causes most properties to
+revert to their default value. Usually @code{\unset} is not
+required as a new @code{\set} command will achieve what is
+wanted.
+
The @code{\set} and @code{\unset} commands can appear anywhere
in the input file and will take effect from the time they are
-encountered until the end of the score or until the property is
-@code{\set} or @code{\unset} again. Let's try changing the
-font size, which affects the size of the note heads (among
+encountered until the end of the score or until the property is
+@code{\set} or @code{\unset} again. Let's try changing the
+font size, which affects the size of the note heads (among
other things) several times. The change is from the default
-value, not the current value.
+value, not the most recently set value.
@lilypond[quote,verbatim,ragged-right,relative=1,fragment]
-c4
+c4
% make note heads smaller
\set fontSize = #-4
d e
% make note heads larger
\set fontSize = #2.5
f g
-% return to original size
+% return to default size
\unset fontSize
a b
@end lilypond
We have now seen how to set the values of several different
-types of property. Note that integers and numbers are alway
-preceded by a hash sign, @code{#}, while a true or false value
-is specified by ##t and ##f, with two hash signs. A text
-property should be enclosed in double quotation signs, as above,
+types of property. Note that integers and numbers are alway
+preceded by a hash sign, @code{#}, while a true or false value
+is specified by ##t and ##f, with two hash signs. A text
+property should be enclosed in double quotation signs, as above,
although we shall see later that text can actually be specified
-in a much more general way by using the very powerful
-@code{markup} command.
+in a much more general way by using the very powerful
+@code{markup} command.
@funindex \with
Context properties may also be set at the time the context is
-created. Sometimes this is a clearer way of specifying a
+created. Sometimes this is a clearer way of specifying a
property value if it is to remain fixed for the duration of
the context. When a context is created with a @code{\new}
-command it may be followed immediately by a
+command it may be followed immediately by a
@code{\with @{ .. @}} block in which the property values are
set. For example, if we wish to suppress the printing of
extra naturals for the duration of a staff we would write:
>>
@end lilypond
-In effect this overrides the default value of the property. It
-may still be changed dynamically using @code{\set} and returned
-to its (new) default value with @code{\unset}.
+Properties set in this way may still be changed dynamically using
+@code{\set} and returned to their default value with @code{\unset}.
+
+The @code{fontSize} property is treated differently. If this is
+set in a @code{\with} clause it effectively resets the default
+value of the font size. If it is later changed with @code{\set}
+this new default value may be restored with the
+@code{\unset fontSize} command.
@node Adding and removing engravers
@subsection Adding and removing engravers
@subsubheading Changing a single context
To remove an engraver from a single context we use the
-@code{\with} command placed immediately after the context creation
+@code{\with} command placed immediately after the context creation
command, as in the previous section.
As an
\remove Staff_symbol_engraver
}
\relative c' {
- c4
+ c4
\set fontSize = #-4 % make note heads smaller
d e
\set fontSize = #2.5 % make note heads larger
@cindex ambitus engraver
-Engravers can also be added to individual contexts.
+Engravers can also be added to individual contexts.
The command to do this is
@code{\consists @emph{Engraver_name}},
\new Voice \with {
\consists Ambitus_engraver
}
- \relative c'' {
+ \relative c'' {
\voiceOne
- c a b g
+ c a b g
}
\new Voice
\relative c' {
@end lilypond
@noindent
-but if we add the Ambitus engraver to the
+but if we add the Ambitus engraver to the
@code{Staff} context it calculates the range from all
the notes in all the voices on that staff:
projects / lilypond.git / commitdiff