@settitle LilyPond internals
-@node Top, LilyPond internals, (dir), (dir)
+@node Top, , (dir), (dir)
@top
-@menu
-* LilyPond internals::
-* Overview::
-* Request_engraver::
-* Coding standards::
-* Making patches::
-* Localisation::
-@end menu
-
-@node LilyPond internals, , Top, Top
-
-@menu
-* Overview:: Overview
-* Request_engraver:: Request_engraver
-@end menu
-
-
-@chapter Getting involved
-
-Please help us make LilyPond a better program. You can help LilyPond in
-several ways. Not all tasks requiring programming or understanding the
-full source code. You can write to the mailing list
-(@email{gnu-music-discuss@@gnu.org} for more information)
-
-@unnumberedsubsec Users
-
-Mutopia needs your help. The mutopia project is a collection of public
-domain sheet music. You can help the project by entering music (either
-by hand, or by converting from scans or MIDI) and submitting it. Point
-your browser to the @uref{http://sca.uwaterloo.ca/Mutopia, Mutopia
-webpage}.
-
-@unnumberedsubsec Font designers
-
-Our set of glyphs (the Feta font) is far from complete. We need the
-following glyphs: segno, coda. The fonts have been coded in MetaFont,
-so you will need to know MetaFont if you want to contribute a glyph.
-
-@unnumberedsubsec Writers
-
-The documentation of LilyPond and related utilities needs a lot of
-work. The documentation is written in
-@uref{http://www.gnu.org/software/texinfo,texinfo}. The documentation of
-LilyPond is sorely lacking in terms of completeness, depth and
-organisation.
-
-Write if you know how to write english documentation in texinfo, and
-know about music and music notation. You must also know how to use
-LilyPond (or be prepared to learn using it). The task is not especially
-hard, but it is a lot of work, and you must be familiar with LilyPond.
-
-@unnumberedsubsec Translators
-
-LilyPond is completely ready for internationalized messages, but there
-are only a few translations so far (dutch, italian, german, japanese,
-french, russian). Translation involves writing a .po file, which is
-relatively easy, and does not even require running LilyPond.
-
-@unnumberedsubsec Hackers
-
-There are lots of possibilities of improving the program itself. There
-are both small projects and big ones. Most of them are listed in our
-TODO file, listed on the homepage of Jan and
-@uref{http://www.cs.uu.nl/~hanwen/lily-devel,Han-Wen}. Modifying
-LilyPond almost always requires patches to the C++ part.
-
-There are also numerous other interesting projects that are more or less
-related to LilyPond
-
-@itemize @bullet
-@item Writing convertors, eg. from NIFF and MIDI (we tried writing one with
-limited success: midi2ly, included with lilypond.)
-
-We found that writing them in Python is the easiest.
-
-@item Writing a GUI frontend to
-LilyPond. At the moment @uref{denemo,denemo.sourceforge.net} is the most
-advanced.
-
-@item Helping write @uref{ http://solfege.sourceforge.net/,solfege
-tools}
-
-@item Helping @uref{primrose.sourceforge.net,primrose}, a tool for
-scanning sheet music.
-@end itemize
-
-
-@chapter LilyPond internals
-
-
-@node Overview, , , Top
-@section Overview
-
-GNU LilyPond is a "multi-pass" system.
-
-@table @samp
-
-@item Parsing:
-
-No difficult algorithms. The .ly file is read, and converted to a list
-of @code{Scores}, which each contain @code{Music} and paper/midi-definitions.
-
-@item Interpreting music
-
-The music is walked through in time-order. The iterators which do the
-walking report Music to Translators which use this information to
-create elements, either MIDI or "visual" elements. The translators
-form a hierarchy; the ones for paper output are Engravers, for MIDI
-Performers.
-
-The translators swallow Music (mostly atomic gobs called Requests),
-create elements, broadcast them to other translators on higher or same
-level in the hierarchy:
-
-The stem of a voice A is broadcast to the staff which contains A, but
-not to the stems, beams and noteheads of a different voice (say B) or
-a different staff. The stem and noteheads of A are coupled, because
-the the Note_heads_engraver broadcasts its heads, and the Stem_engraver catches
-these.
-
-The engraver which agrees to handle a request decides whether to to
-honor the request, ignore it, or merge it with other requests. Merging
-of requests is preferably done with other requests done by members of
-the same voicegroups (beams, brackets, stems). In this way you can put
-the voices of 2 instruments in a conductor's score so they make chords
-(the Beam requests of both instruments will be merged).
-
-@item Prebreaking
-
-Breakable stuff (eg. clefs and bars) are copied into pre and
-postbreaks.
-
-@item Preprocessing
-
-Some dependencies are resolved, such as the direction of stems, beams,
-and "horizontal" placement issues (the order of clefs, keys etc,
-placement of chords in multi-voice music),
-
-@item Break calculation:
-
-The lines and horizontal positions of the columns are determined.
-
-@item Breaking
-
-Through some magical interactions with Line_of_score and Super_elem
-(check out the source) the "lines" are produced.
-
-All other spanners can figure across which lines they are spread. If
-applicable, they break themselves into pieces. After this, each piece
-(or, if there are no pieces, the original spanner itself) throws out
-any dependencies which are in the wrong line.
-
-@item Postprocesing:
-
-Some items and all spanners need computation after the Paper_column
-positions are determined. Examples: slurs, vertical positions of
-staffs.
-
-@item Output paper
-
-@end table
-
-
-@node Request_engraver, , , Top
-@section Request_engraver
-
-In the previous section the idea of Request has been explained, but
-this only solves one half of the problem. The other half is deciding
-which requests should be honored, which should merged with other
-requests, and which should be ignored. Consider this input
-
-@example
-
- \type Staff < % chord
- @{ \meter 2/4; [c8 c8] @}
- @{\meter 2/4; [e8 e8] @}
- >
-
-@end example
-
-Both the cs and es are part of a staff (they are in the same
-Voice_group), so they should share meters, but the two [ ] pairs
-should be merged.
-
-The judge in this "allocation" problem a set of brokers: the requests
-are transmitted to so-called engravers which respond if they want to
-accept a request eg, the @code{Notehead_engraver} will accept
-@code{Note_req}s, and turn down @code{Slur_req}s. If the Music_iterator
-cannot find a engraver that wants the request, it is junked (with a
-warning message).
-
-After all requests have been either assigned, or junked, the Engraver
-will process the requests (which usually means creating an @code{Item}
-or @code{Spanner}). If a @code{Request_engraver} creates something, it
-tells the enclosing context. If all items/spanners have been created,
-then each Engraver is notified of any created Score_element, via a
-broadcasting system.
-
-@unnumberedsubsec example:
-
-@example
-
- c4
-
-@end example
-
-produces:
-
-@example
-
- Note_request (duration 1/4)
- Stem_request (duration 1/4)
-
-@end example
-
-Note_request will be taken by a @code{Notehead_engraver}, stem_request
-will be taken by a @code{Stem_beam_engraver}. @code{Notehead_engraver}
-creates a @code{Notehead}, @code{Stem_beam_engraver} creates a
-@code{Stem}. Both announce this to the Staff_engraver. Staff_engraver
-will tell @code{Stem_beam_engraver} about the @code{Notehead}, which
-will add the @code{Notehead} to the @code{Stem} it just created.
-
-To decide on merging, several engravers have been grouped. Please
-check @file{init/engraver.ly}.
-
-@node Coding standards, , , Top
-
-@chapter CodingStyle - standards while programming for GNU LilyPond
-
-Functions and methods do not return errorcodes: they never crash, but
-report a programming_error and try to carry on.q
-
-
-@unnumberedsubsec Languages
-
-C++ and Python are preferred. Python code should use an indent of 8,
-using TAB characters.
-
-@unnumberedsubsec Filenames
-
-Definitions of classes that are only accessed via pointers
-(*) or references (&) shall not be included as include files.
-
-filenames
-
-@example
- ".hh" Include files
- ".cc" Implementation files
- ".icc" Inline definition files
- ".tcc" non inline Template defs
-@end example
-
-in emacs:
-
-@example
- (setq auto-mode-alist
- (append '(("\\.make$" . makefile-mode)
- ("\\.cc$" . c++-mode)
- ("\\.icc$" . c++-mode)
- ("\\.tcc$" . c++-mode)
- ("\\.hh$" . c++-mode)
- ("\\.pod$" . text-mode)
- )
- auto-mode-alist))
-@end example
-
-
-The class Class_name_abbreviation is coded in @file{class-name-abbr.*}
-
-@unnumberedsubsec Indentation
-
-Standard GNU coding style is used. In emacs:
-
-@example
- (add-hook 'c++-mode-hook
- '(lambda() (c-set-style "gnu")
- )
- )
-@end example
-
-If you like using font-lock, you can also add this to your @file{.emacs}:
-
-@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
-
-@unnumberedsubsec Classes and Types
-
-@example
- This_is_a_class
-@end example
-
-@unnumberedsubsec Members
-
-@example
- Class::member ()
- Type Class::member_type_
- Type Class::member_type ()
-@end example
-
-the @code{type} is a Hungarian notation postfix for @code{Type}. See below
-
-@unnumberedsubsec Macros
-
-Macros should be written completely in uppercase
-
-@unnumberedsubsec Broken code
-
-Broken code (hardwired dependencies, hardwired constants, slow
-algorithms and obvious limitations) should be marked as such: either
-with a verbose TODO, or with a short "ugh" comment.
-
-@unnumberedsec Hungarian notation naming convention
-
-Proposed is a naming convention derived from the so-called
-@emph{Hungarian Notation}. Macros, @code{enum}s and @code{const}s are all
-uppercase, with the parts of the names separated by underscores.
-
-The hungarian notation is to be used when variables are not declared
-near usage (mostly in member variables and functions).
-
-@unnumberedsubsec Types
-
-@table @samp
-@item @code{byte}
- unsigned char. (The postfix _by is ambiguous)
-@item @code{b}
- bool
-@item @code{bi}
- bit
-@item @code{ch}
- char
-@item @code{f}
- float
-@item @code{i}
- signed integer
-@item @code{str}
- string class
-@item @code{sz}
- Zero terminated c string
-@item @code{u}
- unsigned integer
-@end table
-
-@unnumberedsubsec User defined types
-
-@example
-
- /** Slur blah. blah.
- (slur)
- */
- class Slur @{@};
- Slur* slur_p = new Slur;
-
-@end example
-
-@unnumberedsubsec Modifiers
-
-The following types modify the meaning of the prefix.
-These are preceded by the prefixes:
-
-@table @samp
-@item @code{a}
- array
-@item @code{array}
- user built array.
-@item @code{c}
- const. Note that the proper order is @code{Type const}
- i.s.o. @code{const Type}
-@item @code{C}
- A const pointer. This would be equivalent to @code{_c_l}, but since any
- "const" pointer has to be a link (you can't delete a const pointer),
- it is superfluous.
-@item @code{l}
- temporary pointer to object (link)
-@item @code{p}
- pointer to newed object
-@item @code{r}
- reference
-@end table
-
-@unnumberedsubsec Adjective
-
-Adjectives such as global and static should be spelled out in full.
-They come before the noun that they refer to, just as in normal english.
-
-@example
-
-foo_global_i: a global variable of type int commonly called "foo".
-
-@end example
-
-static class members do not need the static_ prefix in the name (the
-Class::var notation usually makes it clear that it is static)
-
-@table @samp
-@item @code{loop_i}
- Variable loop: an integer
-@item @code{u}
- Temporary variable: an unsigned integer
-@item @code{test_ch}
- Variable test: a character
-@item @code{first_name_str}
- Variable first_name: a String class object
-@item @code{last_name_ch_a}
- Variable last_name: a @code{char} array
-@item @code{foo_i_p}
- Variable foo: an @code{Int*} that you must delete
-@item @code{bar_i_l}
- Variable bar: an @code{Int*} that you must not delete
-@end table
-
-Generally default arguments are taboo, except for nil pointers.
-
-The naming convention can be quite conveniently memorised, by
-expressing the type in english, and abbreviating it
-
-@example
-
- static Array<int*> foo
-
-@end example
-
-@code{foo} can be described as "the static int-pointer user-array", so you get
-
-@example
-
- foo_static_l_arr
-
-@end example
-
-
-@unnumberedsec Miscellaneous
-
-For some tasks, some scripts are supplied, notably creating patches, a
-mirror of the website, generating the header to put over cc and hh
-files, doing a release.
-
-Use them.
-
-@node Making patches, , , Top
-
-
-@unnumberedsec Track and distribute your code changes
-
-This page documents how to distribute your changes to GNU lilypond
-
-We would like to have unified context diffs with full pathnames. A
-script automating supplied with Lily.
-
-Distributing a change normally goes like this:
-
-@itemize @bullet
-@item make your fix/add your code
-@item Add changes to CHANGES, and add yourself to Documentation/topdocs/AUTHORS.texi
-@item generate a patch,
-@item e-mail your patch to one of the mailing lists
- gnu-music-discuss@@gnu.org or bug-gnu-music@@gnu.org
-@end itemize
-
-Please do not send entire files, even if the patch is bigger than the
-original. A patch makes it clear what is changed, and it won't
-overwrite previous (not yet released) changes.
-
-@unnumberedsec Generating a patch
-
-Simple version: run
-
-@example
- make -C lilypond-x.y.z/ distclean
- make -C lilypond-x.y.z.NEW/ distclean
- diff -urN lilypond-x.y.z/ lilypond-x.y.z.NEW/
-@end example
-
-Complicated (but automated) version:
-
-In @file{VERSION}, set MY_PATCH_LEVEL:
-
-@example
-
- VERSION:
- ...
- MY_PATCH_LEVEL=jcn1
-
-@end example
-
-In @file{CHANGES}, enter a summary of changes:
-
-@example
- pl 0.1.73.jcn1
- - added PATCHES.texi
-@end example
-
-Then, from the top of Lily's source tree, type
-
-@example
- make release
-@end example
-
-These handy python scripts assume a directory structure which looks
-like:
-
-@example
-
- lilypond -> lilypond-x.y.z # symlink to development directory
- lilypond-x.y.z/ # current development
- patches/ # patches between different releases
- releases/ # .tar.gz releases
-
-@end example
-
-(Some scripts also assume this lives in @file{$HOME/usr/src}).
-
-
-@unnumberedsec Applying patches
-
-
-If you're following LilyPond development regularly, you probably want to
-download just the patch for each subsequent release.
-After downloading the patch (into the patches directory, of course), simply
-apply it:
-
-@example
-
- gzip -dc ../patches/lilypond-0.1.74.diff.gz | patch -p1 -E
-
-@end example
-
-and don't forget to make automatically generated files:
-
-@example
-
- autoconf footnote(patches don't include automatically generated files,
- i.e. file(configure) and files generated by file(configure).)
-
- configure
-
-@end example
-
-@node Localisation, , , Top
-
-@chapter Localisation - User messages in LilyPond
-
-@section Introduction
-
-This document provides some guidelines for uniformising user messages.
-In the absence of other standards, we'll be using these rules when coding
-for for LilyPond@footnote{
-In addition to the C++ coding standards that come with Lily
-}. Hopefully, this can be replaced by general GNU
-guidelines in the future.
-
-Not-preferred messages are marked with @code{+}.
-By convention, agrammatical examples are marked with @code{*}.
-
-
-@section Guidelines
-
-@itemize @bullet
-
-@item
-Every message to the user should be localised (and thus be marked
-for localisation). This includes warning and error messages.
-
-@item
-Don't localise/gettextify:
-
-@itemize @minus
-@item @code{programming_error ()}s
-@item @code{programming_warning ()}s
-@item debug strings
-@item output strings (PostScript, TeX)@footnote{
-This may seem ridiculously obvious, however, makeinfo-3.12s localises
-output strings. Sending bug report now ---jcn
-}
-@end itemize
-
-
-
-@item
-Messages to be localised must be encapsulated in @code{_ (STRING)}
-or @code{_f (FORMAT, ...)}. Eg:
-
-@example
-warning (_ ("Need music in a score"));
-error (_f ("Can't open file: `%s'", file_name));
-@end example
-
-In some rare cases you may need to call @code{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 @code{_i (STRING)}. The @code{_i}
-macro is a no-op, it only serves as a marker for @file{xgettext}.
-
-@example
-char const* messages[] = @{
- _i ("enable debugging output"),
- _i ("ignore lilypond version"),
- 0
-@};
-
-void
-foo (int i)
-@{
- puts (gettext (messages [i]));
-@}
-@end example
-
-See also
-@file{flower/getopt-long.cc} and @file{lily/main.cc}.
-
-@item
-Don't use leading or trailing whitespace in messages.
-
-@item
-Messages containing a final verb, or a gerund (@code{-ing}-form)
-always start with a capital. Other (simpler) messages start with
-a lowercase letter:
-
-@example
-The word `foo' is not declared.
-`foo': not declared.
-Not declaring: `foo'.
-@end example
-
-@item
-To avoid having a number of different messages for the same situation,
-we'll use quoting like this @code{"message: `%s'"} for all strings.
-Numbers are not quoted:
-
-@example
-_f ("Can't open file: `%s'", name_str)
-_f ("Can't find charater number: %d", i)
-@end example
-
-@item
-Think about translation issues.
-In a lot of cases,it's better to translate a whole message.
-The english grammar mustn't be imposed on the translator.
-So, iso
-
-@example
-_ ("Stem at ") + moment.str () + _(" doen't fit in beam")
-@end example
-
-@noindent
-have
-
-@example
-_f ("Stem at %s doen't fit in beam", moment.str ())
-@end example
-
-@item
-Split up multi-sentence messages, whenever possible. Instead of
-
-@example
-warning (_f ("out of tune! Can't find: `%s', "Key_engraver"));
-
-warning (_f ("Can't find font `%s', loading default",
- font_name));
-@end example
-
-@noindent
-rather say:
-
-@example
-warning (_ ("out of tune:");
-warning (_f ("Can't find: `%s', "Key_engraver"));
-
-warning (_f ("Can't find font: `%s', font_name));
-warning (_f ("Loading default font"));
-@end example
-
-@item
-If you must have multiple-sentence messages, use full punctuation.
-Use two spaces after end of sentence punctuation.
-No punctuation (esp. period) is used at the end of simple messages.
-
-@example
- _f ("Non-matching braces in text `%s', adding braces", text)
- _ ("Debug output disabled. Compiled with NPRINT.")
- _f ("Huh? Not a Request: `%s'. Ignoring.", request)
-@end example
-
-@item
-Don't modularise too much; a lot of words cannot be translated
-without context.
-It's probably safe to treat most occurences of words like
-stem, beam, crescendo as separately translatable words.
-
-@item
-When translating, it is preferrable 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
-messages too, of course.
-
-@example
- en: can't open: `foo.ly'
-+ nl: kan `foo.ly' niet openen (1)
- kan niet openen: `foo.ly'* (2)
- niet te openen: `foo.ly'* (3)
-@end example
-
-The first nl message, although gramatically and stylishly correct,
-is not friendly for parsing by humans (even if they speak dutch).
-I guess we'd prefer something like (2) or (3).
-
-@item
-Please don't run make po/po-update with GNU gettext < 0.10.35
-
-@end itemize
-
-@bye
-
-
-
-@bye
-
-
projects / lilypond.git / blobdiff