The GNU debugger, gdb, is the principal tool for debugging C++ code.
-@unnumberedsubsubsec Compiling LilyPond for use with gdb
+@subheading Compiling LilyPond for use with gdb
In order to use gdb with LilyPond, it is necessary to compile
LilyPond with debugging information. This is accomplished by running
with LilyPond. The @var{make install} command will strip debugging
information from the LilyPond binary.
-@unnumberedsubsubsec Typical gdb usage
+@subheading Typical gdb usage
Once you have compiled the Lilypond image with the necessary
debugging information it will have been written to a location in a
This is important as you will need to let gdb know where to find the
image containing the symbol tables. You can invoke gdb from the
-command line using
+command line usinga the following:
@example
gdb out/bin/lilypond
@end example
@noindent
This loads the LilyPond symbol tables into gdb. Then, to run
-LilyPond on @code{test.ly} under the debugger, enter
+LilyPond on @code{test.ly} under the debugger, enter the following:
@example
run test.ly
@end example
+
@noindent
at the gdb prompt.
As an alternative to running gdb at the command line you may try
-a graphical interface to gdb such as ddd
+a graphical interface to gdb such as ddd:
@example
ddd out/bin/lilypond
You can also use sets of standard gdb commands stored in a .gdbinit
file (see next section).
-@unnumberedsubsubsec Typical .gdbinit files
+@subheading Typical .gdbinit files
The behavior of gdb can be readily customized through the use of a
@var{.gdbinit} file. A @var{.gdbinit} file is a file named
interactively using just Guile or you can use the debugging
tools available within Guile.
-@unnumberedsubsubsec Using Guile interactively with LilyPond
+@subheading Using Guile interactively with LilyPond
In order to experiment with Scheme programming in the LilyPond
environment, it is necessary to have a Guile interpreter that
The compilation of the .ly file will then continue.
-@unnumberedsubsubsec Using the Guile debugger
+@subheading Using the Guile debugger
To set breakpoints and/or enable tracing in Scheme functions, put
is processed, a guile prompt will be displayed. You may now enter
commands to set up breakpoints and enable tracing by the Guile debugger.
-@unnumberedsubsubsec Using breakpoints
+@subheading Using breakpoints
At the guile prompt, you can set breakpoints with
the @code{set-break!} procedure:
(set-break! print-book-with)
@end example
-@unnumberedsubsubsec Tracing procedure calls and evaluator steps
+@subheading Tracing procedure calls and evaluator steps
Two forms of trace are available:
its long-term support. This section describes the steps necessary
for feature addition and modification.
+
+@menu
+* Write the code::
+* Write regression tests::
+* Write convert-ly rule::
+* Automaticaly update auxiliary information::
+* Manually update auxiliary information::
+* Edit changes.tely::
+* Verify successful build::
+* Verify regression tests::
+* Post patch for comments::
+* Push patch::
+* Closing the issues::
+@end menu
+
+@node Write the code
@subsection Write the code
You should probably create a new git branch for writing the code, as that
Please be sure to follow the rules for programming style discussed
earlier in this chapter.
+
+@node Write regression tests
@subsection Write regression tests
In order to demonstrate that the code works properly, you will
Use existing regression tests as templates to demonstrate the type of
header information that should be included in a regression test.
+
+@node Write convert-ly rule
@subsection Write convert-ly rule
If the modification changes the input syntax, a convert-ly rule
rule will simply point out to the user that the feature needs
manual correction.
-@subsection Automatically update documentation, snippets, and regtests
+
+@node Automaticaly update auxiliary information
+@subsection Automatically update auxiliary information
convert-ly should be used to update the documentation, the snippets,
and the regression tests. This not only makes the necessary syntax
@end example
-@subsection Manually update documentation, snippets, and regtests
+
+@node Manually update auxiliary information
+@subsection Manually update auxiliary information
Where the convert-ly rule is not able to automatically update the inline
lilypond code in the documentation (i.e. if a NOT_SMART rule is used), the
Where the convert-ly rule is not able to automatically update snippets
in Documentation/snippets/, those snippets must be manually updated.
Those snippets should be copied to Documentation/snippets/new. The
-comments at the top of the snippet describing its automatice generation
+comments at the top of the snippet describing its automatic generation
should be removed. All translated texidoc strings should be removed.
The comment @qq{% begin verbatim} should be removed. The syntax of
the snippet should then be manually edited.
or removed from the documentation should be changed only in
the English version.
+
+@node Edit changes.tely
@subsection Edit changes.tely
An entry should be added to Documentation/changes.tely to describe
The changes.tely entry should be written to show how the new change
improves LilyPond, if possible.
+
+@node Verify successful build
@subsection Verify successful build
When the changes have been made, successful completion must be
Developers on Windows who are unable to build LilyPond should
get help from a Linux or OSX developer to do the make tests.
-@subsection Verify regression test
+
+@node Verify regression tests
+@subsection Verify regression tests
In order to avoid breaking LilyPond, it is important to verify that
the regression tests all succeed. This process is described in
@ref{Regression tests}.
+
+@node Post patch for comments
@subsection Post patch for comments
For any change other than a minor change, a patch set should be
for the same issue can be uploaded by reissuing the git-cl command
with the modified branch checked out.
+
+@node Push patch
@subsection Push patch
Once all the comments have been addressed, the patch can be pushed.
If the author has push privileges, the author will push the patch.
Otherwise, a developer with push privileges will push the patch.
+
+@node Closing the issues
@subsection Closing the issues
Once the patch has been pushed, all the relevant issues should be
should be sent to bug-lilypond requesting the BugMeister to change
the status.
+
@node Iterator tutorial
@section Iterator tutorial
and sent the music events to the appropriate engravers and/or
performers.
+
@node Engraver tutorial
@section Engraver tutorial
made available to the engraver when they are created by other engravers
during the iteration phase.
+
+@menu
+* Useful methods for information processing::
+* Translation process::
+* Preventing garbage collection for SCM member variables::
+* Listening to music events::
+* Acknowledging grobs::
+* Engraver declaration/documentation::
+@end menu
+
+@node Useful methods for information processing
@subsection Useful methods for information processing
An engraver inherits the following public methods from the Translator
translation: for example, an unterminated spanner might be completed
automatically or reported with a warning message.
+
+@node Translation process
@subsection Translation process
At each timestep in the music, translation proceeds by calling the
information has been processed prior to beginning the translation for
the next timestep.
+
+@node Preventing garbage collection for SCM member variables
@subsection Preventing garbage collection for SCM member variables
In certain cases, an engraver might need to ensure private Scheme
@end example
+@node Listening to music events
@subsection Listening to music events
External interfaces to the engraver are implemented by protected
@}
@end example
+
+@node Acknowledging grobs
@subsection Acknowledging grobs
Some engravers also need information from grobs as they are created
@}
@end example
+
+@node Engraver declaration/documentation
@subsection Engraver declaration/documentation
An engraver must have a public macro
and @code{Engraver_writes} is the set of properties written by
the engraver.
+The @code{ADD_ACKNOWLEDGER} and @code{ADD_TRANSLATOR} macros use a
+non-standard indentation system. Each interface, grob, read property,
+and write property is on its own line, and the closing parenthesis
+and semicolon for the macro all occupy a separate line beneath the final
+interface or write property. See existing engraver files for more
+information.
+
+
@node Callback tutorial
@section Callback tutorial
but doesn't yet have a proper home. Ideally, the length of this section
would become zero as items are moved to other homes.
+
+@menu
+* Spacing algorithms::
+* Info from Han-Wen email::
+* Music functions and GUILE debugging::
+@end menu
+
+@node Spacing algorithms
@subsection Spacing algorithms
Here is information from an email exchange about spacing algorithms.
most of them are not drawn. See the break-visibility property in
item-interface.
-@subsection Info from Han-Wen Email
+
+@node Info from Han-Wen email
+@subsection Info from Han-Wen email
In 2004, Douglas Linhardt decided to try starting a document that would
explain LilyPond architecture and design principles. The material below
The headings reflect questions from Doug or comments from Han-Wen;
the body text are Han-Wen's answers.
-@unnumberedsubsubsec Figuring out how things work.
+@subheading Figuring out how things work.
I must admit that when I want to know how a program works, I use grep
and emacs and dive into the source code. The comments and the code
itself are usually more revealing than technical documents.
-@unnumberedsubsubsec What's a grob, and how is one used?
+@subheading What's a grob, and how is one used?
Graphical object - they are created from within engravers, either as
Spanners (derived class) -slurs, beams- or Items (also a derived
contains all items that happen at the same moment). They are separate
classes because they play a special role in the linebreaking process.
-@unnumberedsubsubsec What's a smob, and how is one used?
+@subheading What's a smob, and how is one used?
A C(++) object that is encapsulated so it can be used as a Scheme
object. See GUILE info, "19.3 Defining New Types (Smobs)"
-@unnumberedsubsubsec When is each C++ class constructed and used
+@@subheading When is each C++ class constructed and used
@itemize
@end itemize
-@unnumberedsubsubsec Can you get to Context properties from a Music object?
+@subheading Can you get to Context properties from a Music object?
You can create music object with a Scheme function that reads context
properties (the \applycontext syntax). However, that function is
properties from Music objects, since music objects are not directly
connected to Contexts. That connection is made by the Music_iterators
-@unnumberedsubsubsec Can you get to Music properties from a Context object?
+@subheading Can you get to Music properties from a Context object?
Yes, if you are given the music object within a Context
object. Normally, the music objects enter Contexts in synchronized
fashion, and the synchronization is done by Music_iterators.
-@unnumberedsubsubsec What is the relationship between C++ classes and Scheme objects?
+@subheading What is the relationship between C++ classes and Scheme objects?
Smobs are C++ objects in Scheme. Scheme objects (lists, functions) are
manipulated from C++ as well using the GUILE C function interface
(prefix: scm_)
-@unnumberedsubsubsec How do Scheme procedures get called from C++ functions?
+@subheading How do Scheme procedures get called from C++ functions?
scm_call_*, where * is an integer from 0 to 4.
Also scm_c_eval_string (), scm_eval ()
-@unnumberedsubsubsec How do C++ functions get called from Scheme procedures?
+@subheading How do C++ functions get called from Scheme procedures?
Export a C++ function to Scheme with LY_DEFINE.
-@unnumberedsubsubsec What is the flow of control in the program?
+@subheading What is the flow of control in the program?
Good question. Things used to be clear-cut, but we have Scheme
and SMOBs now, which means that interactions do not follow a very
rigid format anymore. See below for an overview, though.
-@unnumberedsubsubsec Does the parser make Scheme procedure calls or C++ function calls?
+@subheading Does the parser make Scheme procedure calls or C++ function calls?
Both. And the Scheme calls can call C++ and vice versa. It's nested,
with the SCM datatype as lubrication between the interactions
(I think the word "lubrication" describes the process better than the
traditional word "glue")
-@unnumberedsubsubsec How do the front-end and back-end get started?
+@subheading How do the front-end and back-end get started?
Front-end: a file is parsed, the rest follows from that. Specifically,
Paper_lines and other things. This area is still heavily in flux, and
perhaps not something you should want to look at.
-@unnumberedsubsubsec How do the front-end and back-end communicate?
+@subheading How do the front-end and back-end communicate?
There is no communication from backend to front-end. From front-end to
backend is simply the program flow: music + definitions gives
contexts, contexts yield output, after processing, output is written
to disk.
-@unnumberedsubsubsec Where is the functionality associated with KEYWORDs?
+@subheading Where is the functionality associated with KEYWORDs?
See my-lily-lexer.cc (keywords, there aren't that many) and ly/*.ly
(most of the other backslashed \words are identifiers)
-@unnumberedsubsubsec What Contexts/Properties/Music/etc. are available when they are processed?
+@subheading What Contexts/Properties/Music/etc. are available when they are processed?
What do you mean exactly with this question?
See ly/engraver-init.ly for contexts, see scm/define-*.scm for other
objects.
-@unnumberedsubsubsec How do you decide if something is a Music, Context, or Grob property?
+@subheading How do you decide if something is a Music, Context, or Grob property?
Why is part-combine-status a Music property when it seems (IMO)
to be related to the Staff context?
Part_combine_iterator to communicate with Part_combine_engraver.
-@unnumberedsubsubsec I'm adding a property to affect how \autochange works. It seems to
+@subheading Deciding between context and music properties
+
+I'm adding a property to affect how \autochange works. It seems to
me that it should be a context property, but the Scheme autochange
-procecure has a Music argument. Does this mean I should use
+procedure has a Music argument. Does this mean I should use
a Music property?
\autochange is one of these extra strange beasts: it requires
where around-central-C is some function that is called from
make-autochange-music.
-@unnumberedsubsubsec I get lost figuring out what environment the code I'm looking at is in when it executes.
-I found both the C++ and Scheme autochange code. Then I was
-trying to figure out where the code got called from. I finally figured out that
-the Scheme procedure was called before the C++ iterator code, but it took me a
+@subheading How do I tell about the execution environment?
+
+I get lost figuring out what environment the code I'm looking at is in when it
+executes. I found both the C++ and Scheme autochange code. Then I was trying
+to figure out where the code got called from. I finally figured out that the
+Scheme procedure was called before the C++ iterator code, but it took me a
while to figure that out, and I still didn't know who did the calling in the
first place. I only know a little bit about Flex and Bison, so reading those
files helped only a little bit.
this will display OBJ through GUILE.
+@node Music functions and GUILE debugging
@subsection Music functions and GUILE debugging
Ian Hulin was trying to do some debugging in music functions, and
projects / lilypond.git / commitdiff