* Programming without compiling::
* Finding functions::
* Code style::
+* Warnings Errors Progress and Debug Output::
* Debugging LilyPond::
* Tracing object relationships::
* Adding or modifying features::
* Engraver tutorial::
* Callback tutorial::
* LilyPond scoping::
+* Scheme->C interface::
* LilyPond miscellany::
@end menu
begins.
Each type of music event has an associated iterator. Iterators are defined in
-*-iterator.cc. During iteration, an
+@file{*-iterator.cc}. During iteration, an
event's iterator is called to deliver that music event to the appropriate
context(s).
through its two derived classes: Engraver (for graphical output) and
Performer (for midi output).
-Translators are defined in C++ files named *-engraver.cc and *-performer.cc.
+Translators are defined in C++ files named @file{*-engraver.cc}
+and @file{*-performer.cc}.
Much of the work of translating is handled by Scheme functions,
which is one of the keys to LilyPond's exceptional flexibility.
PostScript is used to generate graphical output. A brief PostScript tutorial
is @uref{http://local.wasp.uwa.edu.au/~pbourke/dataformats/postscript/,
available online}. The
-@uref{http://www.adobe.com/devnet/postscript/pdfs/PLRM.pdf, PostScript Lanugage
+@uref{http://www.adobe.com/devnet/postscript/pdfs/PLRM.pdf, PostScript Language
Reference} is available online in PDF format.
@subsection Python
-Python is used for XML2ly and is used for buillding the documentation and the
+Python is used for XML2ly and is used for building the documentation and the
website.
Python documentation is available at @uref{http://www.python.org/doc/,
@node Programming without compiling
@section Programming without compiling
-Much of the development work in LilyPond takes place by changing *.ly or
-*.scm files. These changes can be made without compiling LilyPond. Such
+Much of the development work in LilyPond takes place by changing @file{*.ly} or
+@file{*.scm} files. These changes can be made without compiling LilyPond. Such
changes are described in this section.
Much of LilyPond is written in Scheme or LilyPond input files. These
files are interpreted when the program is run, rather than being compiled
when the program is built, and are present in all LilyPond distributions.
-You will find .ly files in the ly/ directory and the Scheme files in the
-scm/ directory. Both Scheme files and .ly files can be modified and
+You will find @file{.ly} files in the @file{ly/} directory and the Scheme files in the
+@file{scm/} directory. Both Scheme files and @file{.ly} files can be modified and
saved with any text editor. It's probably wise to make a backup copy of
your files before you modify them, although you can reinstall if the
files become corrupted.
When making changes or fixing bugs in LilyPond, one of the initial
challenges is finding out where in the code tree the functions to
be modified live. With nearly 3000 files in the source tree,
-trial-and-error searching is generally ineffective. This section
+trial-and-error searching is generally ineffective. This section
describes a process for finding interesting code.
@subsection Using the ROADMAP
The file ROADMAP is located in the main directory of the lilypond source.
-ROADMAP lists all of the directories in the LilPond source tree, along
+ROADMAP lists all of the directories in the LilyPond source tree, along
with a brief description of the kind of files found in each directory.
This can be a very helpful tool for deciding which directories to search
when looking for a function.
This command will search all the contents of the directory subdirectory/
and display every line in any of the files that contains
-functionName. The @code{-i} option makes @command{grep} ignore
+functionName. The @option{-i} option makes @command{grep} ignore
case -- this can be very useful if you are not yet familiar with
our capitalization conventions.
-The most likely directories to grep for function names are scm/ for
-scheme files, ly/ for lilypond input (*.ly) files, and lily/ for C++
+The most likely directories to grep for function names are @file{scm/} for
+scheme files, ly/ for lilypond input (@file{*.ly}) files, and @file{lily/} for C++
files.
@node Indentation
@subsection Indentation
-Standard GNU coding style is used. In emacs:
+Standard GNU coding style is used.
-@verbatim
- (add-hook 'c++-mode-hook
- '(lambda() (c-set-style "gnu")
- ))
-@end verbatim
-
-If you like using font-lock, you can also add this to your
-@q{.emacs}:
+@subsubheading Indenting files with @code{fixcc.py} (recommended)
-@verbatim
- (setq font-lock-maximum-decoration t)
- (setq c++-font-lock-keywords-3
- (append
- c++-font-lock-keywords-3
- '(("\\b\\(a-zA-Z_?+_\\)\\b" 1 font-lock-variable-name-face) ("\\b\\(A-Z?+a-z_?+\\)\\b" 1 font-lock-type-face))
- ))
-@end verbatim
-
-Some source files may not currently have proper indenting. If this
-is the case, it is desirable to fix the improper indenting when the
-file is modified, with the hope of continually improving the code.
-
-
-@subheading Indenting files with fixcc.py
-
-LilyPond provides a python script that will correct the indentation
-on a c++ file:
+LilyPond provides a python script that will adjust the indentation
+and spacing on a @code{.cc} or @code{.hh} file to very near the
+GNU standard:
@example
-scripts/auxiliar/fixcc.py lily/my-test-file.cc
+scripts/auxiliar/fixcc.py FILENAME
@end example
-Be sure you replace @code{my-test-file.cc} with the name of the file
-that you edited.
-
-If you are editing a file that contains an ADD_TRANSLATOR or ADD_INTERFACE
-macro, the fixcc.py script will move the final parenthesis up one line
-from where it should be. Please check the end of the file before
-you run fixcc.py, and then put the final parenthesis and semicolon
-back on a line by themselves.
+This can be run on all files at once, but this is not recommended
+for normal contributors or developers.
+@smallexample
+scripts/auxiliar/fixcc.py \
+ $(find flower lily -name '*cc' -o -name '*hh' | grep -v /out)
+@end smallexample
-@subheading Indenting files with emacs in script mode
-@c email to wl@gnu.org when I get here.
+@subsubheading Indenting with emacs
-@warning{this is pending some confirmation on -devel. July 2009 -gp}
-
-Command-line script to format stuff with emacs:
+The following hooks will produce indentation which is similar to
+our official indentation as produced with @code{fixcc.py}.
@example
-#!/bin/sh
-emacs $1 -batch --eval '(indent-region (point-min) (point-max) nil)' -f save-buffer
+(add-hook 'c++-mode-hook
+ '(lambda ()
+ (c-set-style "gnu")
+ (setq indent-tabs-mode nil))
@end example
-(that's all on one line)
+If you like using font-lock, you can also add this to your
+@file{.emacs}:
-Save it as a shell script, then run on the file(s) you modified.
+@example
+(setq font-lock-maximum-decoration t)
+(setq c++-font-lock-keywords-3
+ (append
+ c++-font-lock-keywords-3
+ '(("\\b\\(a-zA-Z_?+_\\)\\b" 1 font-lock-variable-name-face) ("\\b\\(A-Z?+a-z_?+\\)\\b" 1 font-lock-type-face))
+ ))
+@end example
@subheading Indenting with vim
-Although emacs indentation is the LilyPond standard, acceptable
+Although emacs indentation is the GNU standard, acceptable
indentation can usually be accomplished with vim. Some hints for
vim are as follows:
A workable .vimrc:
-@verbatim
+@example
set cindent
set smartindent
set autoindent
set ignorecase smartcase
set hlsearch
set confirm
-set statusline=%F%m%r%h%w\ %{&ff}\ %Y\ [ASCII=\%03.3b]\ [HEX=\%02.2B]\ %04l,%04v\ %p%%\ [LEN=%L]
+set statusline=%F%m%r%h%w\ %@{&ff@}\ %Y\ [ASCII=\%03.3b]\ [HEX=\%02.2B]\ %04l,%04v\ %p%%\ [LEN=%L]
set laststatus=2
set number
" Remove trailing whitespace on write
autocmd BufWritePre * :%s/\s\+$//e
-@end verbatim
+@end example
-With this .vimrc, files can be reindented automatically by highlihting
-the lines to be indented in visual mode (use V to enter visual mode)
-and pressing =.
+With this @file{.vimrc}, files can be reindented automatically by
+highlighting the lines to be indented in visual mode (use V to
+enter visual mode) and pressing @code{=}.
-A scheme.vim file will help improve the indentation. This one
-was suggested by Patrick McCarty. It should be saved in
-~/.vim/after/syntax/scheme.vim.
+A @file{scheme.vim} file will help improve the indentation. This
+one was suggested by Patrick McCarty. It should be saved in
+@file{~/.vim/after/syntax/scheme.vim}.
-@verbatim
+@example
" Additional Guile-specific 'forms'
-syn keyword schemeSyntax define-public define* define-safe-public
+syn keyword schemeSyntax define-public define*-public
+syn keyword schemeSyntax define* lambda* let-keywords*
+syn keyword schemeSyntax defmacro defmacro* define-macro
+syn keyword schemeSyntax defmacro-public defmacro*-public
syn keyword schemeSyntax use-modules define-module
-syn keyword schemeSyntax defmacro-public define-macro
-syn keyword schemeSyntax define-markup-command
-syn keyword schemeSyntax define-markup-list-command
-syn keyword schemeSyntax let-keywords* lambda* define*-public
-syn keyword schemeSyntax defmacro* defmacro*-public
+syn keyword schemeSyntax define-method define-class
+
+" Additional LilyPond-specific 'forms'
+syn keyword schemeSyntax define-markup-command define-markup-list-command
+syn keyword schemeSyntax define-safe-public define-music-function
+syn keyword schemeSyntax def-grace-function
" All of the above should influence indenting too
-set lw+=define-public,define*,define-safe-public,use-modules,define-module
-set lw+=defmacro-public,define-macro
+set lw+=define-public,define*-public
+set lw+=define*,lambda*,let-keywords*
+set lw+=defmacro,defmacro*,define-macro
+set lw+=defmacro-public,defmacro*-public
+set lw+=use-modules,define-module
+set lw+=define-method,define-class
set lw+=define-markup-command,define-markup-list-command
-set lw+=let-keywords*,lambda*,define*-public,defmacro*,defmacro*-public
+set lw+=define-safe-public,define-music-function
+set lw+=def-grace-function
" These forms should not influence indenting
set lw-=if
" Try to highlight all ly: procedures
syn match schemeFunc "ly:[^) ]\+"
-@end verbatim
+@end example
@node Naming conventions
guide helping programmers writing consistent messages for all GNU
programs.
-Non-preferred messages are marked with `+'. By convention,
+Non-preferred messages are marked with `+'. By convention,
ungrammatical examples are marked with `*'. However, such ungrammatical
examples may still be preferred.
@item
Every message to the user should be localized (and thus be marked
-for localization). This includes warning and error messages.
+for localization). This includes warning and error messages.
@item
Do not localize/gettextify:
error (_f ("cannot open file: `%s'", file_name));
@end example
-In some rare cases you may need to call `gettext ()' by hand. This
+In some rare cases you may need to call `gettext ()' by hand. This
happens when you pre-define (a list of) string constants for later
-use. In that case, you'll probably also need to mark these string
-constants for translation, using `_i (STRING)'. The `_i' macro is
+use. In that case, you'll probably also need to mark these string
+constants for translation, using `_i (STRING)'. The `_i' macro is
a no-op, it only serves as a marker for `xgettext'.
@example
@}
@end example
-See also `flower/getopt-long.cc' and `lily/main.cc'.
+See also @file{flower/getopt-long.cc} and @file{lily/main.cc}.
@item
-Do not use leading or trailing whitespace in messages. If you need
+Do not use leading or trailing whitespace in messages. If you need
whitespace to be printed, prepend or append it to the translated
message
@end example
Messages containing a final verb, or a gerund (`-ing'-form) always
-start with a capital. Other (simpler) messages start with a
+start with a capital. Other (simpler) messages start with a
lowercase letter
@example
rather than `can't' or `don't'
To avoid having a number of different messages for the same
situation, well will use quoting like this `"message: `%s'"' for all
-strings. Numbers are not quoted:
+strings. Numbers are not quoted:
@example
_f ("cannot open file: `%s'", name_str)
@end example
@item
-Think about translation issues. In a lot of cases, it is better to
-translate a whole message. The english grammar must not be imposed
-on the translator. So, instead of
+Think about translation issues. In a lot of cases, it is better to
+translate a whole message. English grammar must not be imposed on the
+translator. So, instead of
@example
stem at + moment.str () + does not fit in beam
@end example
@item
-Split up multi-sentence messages, whenever possible. Instead of
+Split up multi-sentence messages, whenever possible. Instead of
@example
warning (_f ("out of tune! Can't find: `%s'", "Key_engraver"));
@item
If you must have multiple-sentence messages, use full punctuation.
-Use two spaces after end of sentence punctuation. No punctuation
+Use two spaces after end of sentence punctuation. No punctuation
(esp. period) is used at the end of simple messages.
@example
@item
Do not modularize too much; words frequently cannot be translated
-without context. It is probably safe to treat most occurences of
+without context. It is probably safe to treat most occurrences of
words like stem, beam, crescendo as separately translatable words.
@item
When translating, it is preferable to put interesting information
at the end of the message, rather than embedded in the middle.
This especially applies to frequently used messages, even if this
-would mean sacrificing a bit of eloquency. This holds for original
+would mean sacrificing a bit of eloquency. This holds for original
messages too, of course.
@example
The first nl message, although grammatically and stylistically
correct, is not friendly for parsing by humans (even if they speak
-dutch). I guess we would prefer something like (2) or (3).
+dutch). I guess we would prefer something like (2) or (3).
@item
Do not run make po/po-update with GNU gettext < 0.10.35
@end itemize
+@node Warnings Errors Progress and Debug Output
+@section Warnings, Errors, Progress and Debug Output
+
+@unnumberedsubsec Available log levels
+
+LilyPond has several loglevels, which specify how verbose the output on
+the console should be:
+@itemize
+@item NONE: No output at all, even on failure
+@item ERROR: Only error messages
+@item WARN: Only error messages and warnings
+@item BASIC_PROGRESS: Warnings, errors and basic progress (success, etc.)
+@item PROGRESS: Warnings, errors and full progress messages
+@item INFO: Warnings, errors, progress and more detailed information (default)
+@item DEBUG: All messages, including vull debug messages (very verbose!)
+@end itemize
+
+The loglevel can either be set with the environment variable
+@code{LILYPOND_LOGLEVEL} or on the command line with the @option{--loglevel=...}
+option.
+
+@unnumberedsubsec Functions for debug and log output
+
+LilyPond has two different types of error and log functions:
+@itemize
+
+@item
+If a warning or error is caused by an identified position in the input file,
+e.g. by a grob or by a music expression, the functions of the @code{Input}
+class provide logging functionality that prints the position of the message
+in addition to the message.
+
+@item
+If a message can not be associated with a particular position in an input file,
+e.g. the output file cannot be written, then the functions in the
+@code{flower/include/warn.hh} file will provide logging functionality that
+only prints out the message, but no location.
+
+@end itemize
+
+There are also Scheme functions to access all of these logging functions from
+scheme. In addition, the Grob class contains some convenience wrappers for
+even easier access to these functions.
+
+The message and debug functions in @code{warn.hh} also have an optional
+argument @code{newline}, which specifies whether the message should always
+start on a new line or continue a previous message.
+By default, @code{progress_indication} does NOT start on a new line, but rather
+continue the previous output. They also do not have a particular input
+position associated, so there are no progress functions in the Input class.
+All other functions by default start their output on a new line.
+
+The error functions come in three different flavors: fatal error messages,
+programming error messages and normal error messages. Errors written
+by the @code{error ()} function will cause LilyPond to exit immediately,
+errors by @code{Input::error ()} will continue the compilation, but
+return a non-zero return value of the lilypond call (i.e. indicate an
+unsuccessful program execution). All other errors will be printed on the
+console, but not exit LilyPond or indicate an unsuccessful return code.
+Their only differences to a warnings are the displayed text and that
+they will be shown with loglevel @code{ERROR}.
+
+If the Scheme option @code{warning-as-error} is set, any warning will be
+treated as if @code{Input::error} was called.
+
+
+@unnumberedsubsec All logging functions at a glance
+
+@multitable @columnfractions 0.16 0.42 0.42
+@headitem
+@tab C++, no location
+@tab C++ from input location
+
+@item ERROR
+@tab @code{error ()}, @code{programming_error (msg)}, @code{non_fatal_error (msg)}
+@tab @code{Input::error (msg)}, @code{Input::programming_error (msg)}
+
+@item WARN
+@tab @code{warning (msg)}
+@tab @code{Input::warning (msg)}
+
+@item BASIC
+@tab @code{basic_progress (msg)}
+@tab -
+
+@item PROGRESS
+@tab @code{progress_indication (msg)}
+@tab -
+
+@item INFO
+@tab @code{message (msg)}
+@tab @code{Input::message (msg)}
+
+@item DEBUG
+@tab @code{debug_output (msg)}
+@tab @code{Input::debug_output (msg)}
+
+@item @tab @tab
+
+@headitem
+@tab C++ from a Grob
+@tab Scheme, music expression
+
+@item ERROR
+@tab @code{Grob::programming_error (msg)}
+@tab -
+
+@item WARN
+@tab @code{Grob::warning (msg)}
+@tab @code{(ly:music-warning music msg)}
+
+@item BASIC
+@tab -
+@tab -
+
+@item PROGRESS
+@tab -
+@tab -
+
+@item INFO
+@tab -
+@tab @code{(ly:music-message music msg)}
+
+@item DEBUG
+@tab -
+@tab -
+
+@item @tab @tab
+
+@headitem
+@tab Scheme, no location
+@tab Scheme, input location
+
+@item ERROR
+@tab -
+@tab @code{(ly:error msg args)}, @code{(ly:programming-error msg args)}
+
+@item WARN
+@tab @code{(ly:warning msg args)}
+@tab @code{(ly:input-warning input msg args)}
+
+@item BASIC
+@tab @code{(ly:basic-progress msg args)}
+@tab -
+
+@item PROGRESS
+@tab @code{(ly:progress msg args)}
+@tab -
+
+@item INFO
+@tab @code{(ly:message msg args)}
+@tab @code{(ly:input-message input msg args)}
+
+@item DEBUG
+@tab @code{(ly:debug msg args)}
+@tab -
+
+@end multitable
+
+
+
@node Debugging LilyPond
@section Debugging LilyPond
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 usinga the following:
+command line using 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 the following:
+LilyPond on @file{test.ly} under the debugger, enter the following:
@example
run test.ly
has all the LilyPond modules loaded. This requires the following
steps.
-First, define a Scheme symbol for the active module in the .ly file:
+First, define a Scheme symbol for the active module in the @file{.ly} file:
@example
#(module-define! (resolve-module '(guile-user))
'lilypond-module (current-module))
@end example
-Now place a Scheme function in the .ly file that gives an
+Now place a Scheme function in the @file{.ly} file that gives an
interactive Guile prompt:
@example
#(top-repl)
@end example
-When the .ly file is compiled, this causes the compilation to be
+When the @file{.ly} file is compiled, this causes the compilation to be
interrupted and an interactive guile prompt to appear. Once the
guile prompt appears, the LilyPond active module must be set as the
current guile module:
guile> (quit)
@end example
-The compilation of the .ly file will then continue.
+The compilation of the @file{.ly} file will then continue.
@subheading Using the Guile debugger
command at the guile prompt.
Embedding breakpoint commands like this is particularly useful if
-you want to look at how the Scheme procedures in the @var{.scm}
+you want to look at how the Scheme procedures in the @file{.scm}
files supplied with LilyPond work. To do this, edit the file in
the relevant directory to add this line near the top:
Now you can set a breakpoint after the procedure you are interested
in has been declared. For example, if you are working on routines
-called by @var{print-book-with} in @var{lily-library.scm}:
+called by @var{print-book-with} in @file{lily-library.scm}:
@example
(define (print-book-with parser book process-procedure)
@section Tracing object relationships
Understanding the LilyPond source often boils down to figuring out what
-is happening to the Grobs. Where (and why) are they being created,
+is happening to the Grobs. Where (and why) are they being created,
modified and destroyed? Tracing Lily through a debugger in order to
identify these relationships can be time-consuming and tedious.
In order for the Graphviz tool to work, config.make must be modified.
It is probably a good idea to first save a copy of config.make under
-a different name. Then, edit config.make by removing every occurence
-of @code{-DNDEBUG}.
+a different name. Then, edit config.make by removing every occurrence
+of @option{-DNDEBUG}.
@item Rebuilding LilyPond
make -C lily clean && make -C lily
@end example
-@item Create a graphviz-compatible .ly file
+@item Create a graphviz-compatible @file{.ly} file
-In order to use the graphviz utility, the .ly file must include
+In order to use the graphviz utility, the @file{.ly} file must include
@file{ly/graphviz-init.ly}, and should then specify the
grobs and symbols that should be tracked. An example of this
is found in @file{input/regression/graphviz.ly}.
The logfile has standard lilypond output, as well as the Graphviz
output data. Delete everything from the beginning of the file
-up to but not including the first occurence of @code{digraph}.
+up to but not including the first occurrence of @code{digraph}.
+
+Also, delete the final liypond message about successs from the end
+of the file.
@item Process the logfile with @code{dot}
The pdf file can then be viewed with any pdf viewer.
-When compiled without @code{-DNDEBUG}, lilypond may run slower
+When compiled without @option{-DNDEBUG}, lilypond may run slower
than normal. The original configuration can be restored by either
renaming the saved copy of @code{config.make} or rerunning
@code{configure}. Then rebuild lilypond with
* Write the code::
* Write regression tests::
* Write convert-ly rule::
-* Automaticaly update auxiliary information::
-* Manually update auxiliary information::
+* Automatically update documentation::
+* Manually update documentation::
* Edit changes.tely::
* Verify successful build::
* Verify regression tests::
In order to demonstrate that the code works properly, you will
need to write one or more regression tests. These tests are
-typically .ly files that are found in input/regression.
+typically @file{.ly} files that are found in @file{input/regression}.
Regression tests should be as brief as possible to demonstrate the
functionality of the code.
rule will simply point out to the user that the feature needs
manual correction.
+@subsubheading Updating version numbers
-@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
-changes, it also tests the convert-ly rules.
-
-The automatic updating is a three step process. First, be sure you
-are in the top-level source directory. Then, for the
-documentation, do:
+If a development release occurs between you writing your patch and
+having it approved+pushed, you will need to update the version
+numbers in your tree. This can be done with:
@example
-find Documentation/ -name '*.itely' | xargs convert-ly -e --from @qq{@var{X.Y.Z}}
+scripts/auxiliar/update-patch-version old.version.number new.version.number
@end example
-@noindent
-where @var{X.Y.Z} is the version number of the last released development
-version.
+It will change all files in git, so use with caution and examine
+the resulting diff.
+
+
+@node Automatically update documentation
+@subsection Automatically update documentation
+
+@command{convert-ly} should be used to update the documentation,
+the snippets, and the regression tests. This not only makes the
+necessary syntax changes, it also tests the @command{convert-ly}
+rules.
-Next, for the snippets, do:
+The automatic updating is performed by moving to the top-level
+source directory, then running:
@example
-find Documentation/snippets/ -name '*.ly' | xargs convert-ly -e --from @qq{@var{X.Y.Z}}
+scripts/auxiliar/update-with-convert-ly.sh
@end example
-Finally, for the regression tests, do:
+If you did an out-of-tree build, pass in the relative path:
@example
-find input/regression/ -name '*.ly' | xargs convert-ly -e --from @qq{@var{X.Y.Z}}
-
+BUILD_DIR=../build-lilypond/ scripts/auxiliar/update-with-convert-ly.sh
@end example
-@node Manually update auxiliary information
-@subsection Manually update auxiliary information
+@node Manually update documentation
+@subsection Manually update documentation
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
In order to avoid breaking LilyPond, it is important to verify that
the regression tests succeed, and that no unwanted changes are
introduced into the output. This process is described in
-@ref{Identifying code regressions}.
+@ref{Regtest comparison}.
@subheading Typical developer's edit/compile/test cycle
@node Post patch for comments
@subsection Post patch for comments
-For any change other than a minor change, a patch set should be
-posted on @uref{http://codereview.appspot.com/, Rietveld} for comment.
-This requires the use of an external package, git-cl, and an email
-account on Google.
-
-git-cl is installed by:
-
-@example
-git clone git://neugierig.org/git-cl.git
-@end example
-
-Then, add the git-cl directory to your PATH, or create a
-symbolic link to the git-cl and upload.py in one of your
-PATH directories (like usr/bin). git-cl is then
-configured by entering the command
-
-@example
-git cl config
-@end example
-
-@noindent
-in the LilyPond git directory and answering the questions that
-are asked. If you do not understand the question answer with just
-a newline (CR).
-
-The patch set is posted to Rietveld as follows. Ensure your changes
-are committed in a separate branch, which should differ from the
-reference branch to be used by just the changes to be uploaded.
-If the reference branch is to be origin/master, ensure this is
-up-to-date. If necessary, use git rebase to rebase the branch
-containing the changes to the head of origin/master. Finally,
-check out branch with the changes and enter the command:
-
-@example
-git cl upload <reference SHA1 ID>
-@end example
-
-@noindent
-where <reference SHA1 ID> is the SHA1 ID of the commit to be used
-as a reference source for the patch. Generally, this will be the
-SHA1 ID of origin/master, and in that case the command
-
-@example
-git cl upload origin/master
-@end example
-
-@noindent
-can be used.
-
-After prompting for your Google email address and password, the
-patch set will be posted to Rietveld.
-
-You should then announce the patch by sending
-an email to lilypond-devel, with a subject line
-starting with PATCH:, asking for comments on the patch.
-
-As revisions are made in response to comments, successive patch sets
-for the same issue can be uploaded by reissuing the git-cl command
-with the modified branch checked out.
-
-Sometimes in response to comments on revisions, the best way to
-work may require creation of a new branch in git. In order to
-associate the new branch with an existing Reitveld issue,
-the following command can be used:
-
-@example
-git cl issue issue-number
-@end example
-
-@noindent
-where @code{issue-number} is the number of the existing Rietveld
-issue.
-
+See @ref{Uploading a patch for review}.
@node Push patch
Once the patch has been pushed, all the relevant issues should be
closed.
-On Rietveld, the author should log in an close the issue either by
+On Rietveld, the author should log in and close the issue either by
using the @q{Edit Issue} link, or by clicking the circled x icon
to the left of the issue name.
@}
@end example
+Acknowledge functions are called in the order engravers are
+@code{\consist}-ed (the only exception is if you set
+@code{must-be-last} to @code{#t}).
+
+If useful things are to be done to the acknowledged grobs, this
+should be deferred until all the acknowledging has finished, i.e.,
+store the acknowledged grobs and process the information in a
+@code{process-acknowledged ()} or @code{stop-translation-timestep ()}
+function.
+
@node Engraver declaration/documentation
@subsection Engraver declaration/documentation
@node LilyPond scoping
@section LilyPond scoping
-The Lilypond language has a concept of scoping, ie you can do
+The Lilypond language has a concept of scoping, i.e. you can do
@example
foo = 1
dispersed, either by being stored module-locally, or in weak hash
tables.
+
+@node Scheme->C interface
+@section Scheme->C interface
+
+Most of the C functions interfacing with Guile/Scheme used in LilyPond
+are described in the API Reference of the
+@uref{http://www.gnu.org/software/guile/manual/html_node/index.html,
+GUILE Reference Manual}.
+
+The remaining functions are defined in @file{lily/lily-guile.cc},
+@file{lily/include/lily-guile.hh} and
+@file{lily/include/lily-guile-macros.hh}.
+Although their names are meaningful there's a few things you should know
+about them.
+
+@menu
+* Comparison::
+* Conversion::
+@end menu
+
+@node Comparison
+@subsection Comparison
+
+This is the trickiest part of the interface.
+
+Mixing Scheme values with C comparison operators won't produce any crash
+or warning when compiling but must be avoided:
+
+@example
+scm_string_p (scm_value) == SCM_BOOL_T
+@end example
+
+As we can read in the reference, @code{scm_string_p} returns a Scheme
+value: either @code{#t} or @code{#f} which are written @code{SCM_BOOL_T}
+and @code{SCM_BOOL_F} in C. This will work, but it is not following
+to the API guidelines. For further information, read this discussion:
+
+@smallexample
+@uref{http://lists.gnu.org/archive/html/lilypond-devel/2011-08/msg00646.html}
+@end smallexample
+
+There are functions in the Guile reference that returns C values
+instead of Scheme values. In our example, a function called
+@code{scm_is_string} (described after @code{string?} and @code{scm_string_p})
+returns the C value 0 or 1.
+
+So the best solution was simply:
+
+@example
+scm_is_string (scm_value)
+@end example
+
+There a simple solution for almost every common comparison. Another example:
+we want to know if a Scheme value is a non-empty list. Instead of:
+
+@example
+(scm_is_true (scm_list_p (scm_value)) && scm_value != SCM_EOL)
+@end example
+
+one can usually use:
+
+@example
+scm_is_pair (scm_value)
+@end example
+
+since a list of at least one member is a pair. This test is
+cheap; @code{scm_list_p} is actually quite more complex since it makes
+sure that its argument is neither a `dotted list' where the last pair
+has a non-null @code{cdr}, nor a circular list. There are few
+situations where the complexity of those tests make sense.
+
+Unfortunately, there is not a @code{scm_is_[something]} function for
+everything. That's one of the reasons why LilyPond has its own Scheme
+interface. As a rule of thumb, tests that are cheap enough to be
+worth inlining tend to have such a C interface. So there is
+@code{scm_is_pair} but not @code{scm_is_list}, and @code{scm_is_eq}
+but not @code{scm_is_equal}.
+
+@subheading General definitions
+
+@subsubheading bool to_boolean (SCM b)
+
+Return @code{true} if @var{b} is @code{SCM_BOOL_T}, else return @code{false}.
+
+This should be used instead of @code{scm_is_true} and
+@code{scm_is_false} for properties since in Lilypond, unset properties
+are read as an empty list, and by convention unset Boolean properties
+default to false. Since both @code{scm_is_true} and
+@code{scm_is_false} only compare with @code{##f} in line with what
+Scheme's conditionals do, they are not really useful for checking the
+state of a Boolean property.
+
+@subsubheading bool ly_is_[something] (args)
+
+Behave the same as scm_is_[something] would do if it existed.
+
+@subsubheading bool is_[type] (SCM s)
+
+Test whether the type of @var{s} is [type].
+[type] is a LilyPond-only set of values (direction, axis...). More
+often than not, the code checks Lilypond specific C++-implemented
+types using
+
+@subsubheading [type *] unsmob_[type] (SCM s)
+
+This tries converting a Scheme object to a pointer of the desired
+kind. If the Scheme object is of the wrong type, a pointer value
+of@w{ }@code{0} is returned, making this suitable for a Boolean test.
+
+@node Conversion
+@subsection Conversion
+
+@subheading General definitions
+
+@subsubheading bool to_boolean (SCM b)
+
+Return @code{true} if @var{b} is @code{SCM_BOOL_T}, else return @code{false}.
+
+This should be used instead of @code{scm_is_true} and @code{scm_is_false}
+for properties since empty lists are sometimes used to unset them.
+
+@subsubheading [C type] ly_scm2[C type] (SCM s)
+
+Behave the same as scm_to_[C type] would do if it existed.
+
+@subsubheading [C type] robust_scm2[C type] (SCM s, [C type] d)
+
+Behave the same as scm_to_[C type] would do if it existed.
+Return @var{d} if type verification fails.
+
+
@node LilyPond miscellany
@section LilyPond miscellany
Joe Neeman answered:
We create lots of extra grobs (eg. a BarNumber at every bar line) but
-most of them are not drawn. See the break-visibility property in
+most of them are not drawn. See the break-visibility property in
item-interface.
+Here is another e-mail exchange. Janek WarchoĊ asked for a starting point
+to fixing 1301 (change clef colliding with notes). Neil Puttock replied:
+
+The clef is on a loose column (it floats before the head), so the
+first place I'd look would be lily/spacing-loose-columns.cc (and
+possibly lily/spacing-determine-loose-columns.cc).
+I'd guess the problem is the way loose columns are spaced between
+other columns: in this snippet, the columns for the quaver and tuplet
+minim are so close together that the clef's column gets dumped on top
+of the quaver (since it's loose, it doesn't influence the spacing).
@node Info from Han-Wen email
@subsection Info from Han-Wen email
@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
+and emacs and dive into the source code. The comments and the code
itself are usually more revealing than technical documents.
@subheading What's a grob, and how is one used?
class) -notes, clefs, etc.
There are two other derived classes System (derived from Spanner,
-contaning a "line of music") and Paper_column (derived from Item, it
-contains all items that happen at the same moment). They are separate
+containing a "line of music") and Paper_column (derived from Item, it
+contains all items that happen at the same moment). They are separate
classes because they play a special role in the linebreaking process.
@subheading What's a smob, and how is one used?
Engravers
Executive branch of Contexts, plugins that create grobs, usually one
-engraver per grob type. Created together with context.
+engraver per grob type. Created together with context.
@item
Layout Objects
@item
Grob Interfaces
-These are not C++ classes per se. The idea of a Grob interface hasn't
-crystallized well. ATM, an interface is a symbol, with a bunch of grob
-properties. They are not objects that are created or destroyed.
+These are not C++ classes per se. The idea of a Grob interface hasn't
+crystallized well. ATM, an interface is a symbol, with a bunch of grob
+properties. They are not objects that are created or destroyed.
@item
Iterators
@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 (the \applycontext syntax). However, that function is
executed during Interpreting, so you can not really get Context
properties from Music objects, since music objects are not directly
-connected to Contexts. That connection is made by the Music_iterators
+connected to Contexts. That connection is made by the Music_iterators
@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
+object. Normally, the music objects enter Contexts in synchronized
fashion, and the synchronization is done by Music_iterators.
@subheading What is the relationship between C++ classes and Scheme objects?
-Smobs are C++ objects in Scheme. Scheme objects (lists, functions) are
+Smobs are C++ objects in Scheme. Scheme objects (lists, functions) are
manipulated from C++ as well using the GUILE C function interface
(prefix: scm_)
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.
+rigid format anymore. See below for an overview, though.
@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,
+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
@subheading How do the front-end and back-end get started?
-Front-end: a file is parsed, the rest follows from that. Specifically,
+Front-end: a file is parsed, the rest follows from that. Specifically,
Parsing leads to a Music + Music_output_def object (see parser.yy,
definition of toplevel_expression )
ly_run_translator ())
During interpreting, Global_context + Music leads to a bunch of
-Contexts. (see Global_translator::run_iterator_on_me () )
+Contexts (see Global_translator::run_iterator_on_me ()).
After interpreting, Global_context contains a Score_context (which
-contains staves, lyrics etc.) as a child. Score_context::get_output ()
+contains staves, lyrics etc.) as a child. Score_context::get_output ()
spews a Music_output object (either a Paper_score object for notation
or Performance object for MIDI).
-The Music_output object is the entry point for the backend. (see
-ly_render_output () )
+The Music_output object is the entry point for the backend (see
+ly_render_output ()).
The main steps of the backend itself are in
@itemize
@item
-paper-score.cc , Paper_score::process_
+@file{paper-score.cc} , Paper_score::process_
@item
-system.cc , System::get_lines()
+@file{system.cc} , System::get_lines()
@item
The step, where things go from grobs to output, is in
System::get_line(): each grob delivers a Stencil (a Device
independent output description), which is interpreted by our
-outputting backends (scm/output-tex.scm and scm/output-ps.scm)
-to produce TeX and PS.
+outputting backends (@file{scm/output-tex.scm} and
+@file{scm/output-ps.scm}) to produce TeX and PS.
@end itemize
Interactions between grobs and putting things into .tex and .ps files
-have gotten a little more complex lately. Jan has implemented
+have gotten a little more complex lately. Jan has implemented
page-breaking, so now the backend also involves Paper_book,
-Paper_lines and other things. This area is still heavily in flux, and
+Paper_lines and other things. This area is still heavily in flux, and
perhaps not something you should want to look at.
@subheading How do the front-end and back-end communicate?
-There is no communication from backend to front-end. From front-end to
+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.
@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)
+See @file{my-lily-lexer.cc} (keywords, there aren't that many)
+and @file{ly/*.ly} (most of the other backslashed @code{/\words} are identifiers)
@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.
+See @file{ly/engraver-init.ly} for contexts,
+see @file{scm/define-*.scm} for other objects.
@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)
Engravers and Contexts
Music_iterators can send "synthetic" music events (which aren't in
-the input) to a context. These are caught by Engravers. This is
+the input) to a context. These are caught by Engravers. This is
mostly a one way communication channel.
part-combine-status is part of such a synthetic event, used by
a Music property?
\autochange is one of these extra strange beasts: it requires
-look-ahead to decide when to change staves. This is achieved by
-running the interpreting step twice (see scm/part-combiner.scm , at
-the bottom), and storing the result of the first step (where to switch
+look-ahead to decide when to change staves. This is achieved by
+running the interpreting step twice (see
+@file{scm/part-combiner.scm} , at the bottom), and
+storing the result of the first step (where to switch
staves) in a Music property. Since you want to influence that
where-to-switch list, your must affect the code in
-make-autochange-music (scm/part-combiner.scm). That code is called
-directly from the parser and there are no official "parsing
-properties" yet, so there is no generic way to tune \autochange. We
-would have to invent something new for this, or add a separate
-argument,
+make-autochange-music (@file{scm/part-combiner.scm}).
+That code is called directly from the parser and there are no
+official "parsing properties" yet, so there is no generic way
+to tune \autochange. We would have to invent something new
+for this, or add a separate argument,
@example
\autochange #around-central-C ..music..
-> the second c' remains untransposed.
-Take a look at lily/music.cc to see where the transposition takes place.
+Take a look at @file{lily/music.cc} to see where the transposition takes place.
@subheading How do I tell about the execution environment?
first place. I only know a little bit about Flex and Bison, so reading those
files helped only a little bit.
-@emph{Han-Wen:} GDB can be of help here. Set a breakpoint in C++, and run. When you
-hit the breakpoint, do a backtrace. You can inspect Scheme objects
+@emph{Han-Wen:} GDB can be of help here. Set a breakpoint in C++, and run. When you
+hit the breakpoint, do a backtrace. You can inspect Scheme objects
along the way by doing
@example
Han-Wen answered as follows:
-You can see the defintion by doing
+You can see the definition by doing
@example
#(display conditionalMark)
@end example
noindent
-inside the .ly file.
+inside the @file{.ly} file.
The breakpoint failing may have to do with the call sequence. See
-parser.yy, run_music_function(). The function is called directly from
+@file{parser.yy}, run_music_function(). The function is called directly from
C++, without going through the GUILE evaluator, so I think that is why
there is no debugger trap.
projects / lilypond.git / blobdiff