+mailto(gnu-music-discuss@gnu.org)
COMMENT(-*-text-*-)
redef(var)(1)(whenlatex(latexcommand({\normalfont\scshape )ARG1+latexcommand(}))\
\score {
\notes
\relative c'' {
- \key g;
- \time 3/4;
-
- d4 [g,8 a b c] d4 g, g |
- e'4 [c8 d e fis] g4 g, g |
- c4 [d8( )c b a( ] )b4 [c8 b a g] |
- a4 [b8 a g fis] g2. |
+ \key g;
+ \time 3/4;
- \bar ":|";
+ \repeat 2 {
+ d4 [g,8 a b c] d4 g, g |
+ e'4 [c8 d e fis] g4 g, g |
+ c4 [d8( )c b a( ] )b4 [c8 b a g] |
+ a4 [b8 a g fis] g2. |
+ }
b'4 [g8 a b g]
a4 [d,8 e fis d] |
this command comes after the code(\time) command, in the
output, the key comes before the time signature: LilyPond knows about
music typesetting conventions.
+verb(
+ \repeat 2 {
+) COMMENT(
+
+) This command tells LilyPond that the enclosed piece of music must
+be played twice.
verb(
d4
) COMMENT(
[g,8
)COMMENT(
-)The open bracket starts a beam. This bracket is connected to the
+)The open bracket starts a beam. Lily can set beams automatically,
+but we want to specify them ourselves. This bracket is connected to the
following note, which is an eighth with pitch code(g') (remember
relative mode for pitches!)
COMMENT(
done for two slurs. Note that parentheses (slur markers) are between
the notes, and the brackets (beam markers) around the notes. As you
can see, the brackets and parentheses do not have to nest.
-
verb(
a4 [b8 a g fis] g2. |
) COMMENT(
) A duration that is to be augmented with a duration dot, is notated
with a duration number followed by periods, as many as you want
-augmentation dots.COMMENT(
-
-)verb(
- \bar ":|"; % a repeat sign
+augmentation dots.
+verb(
+ }
) COMMENT(
-)
-Lily can not detect where you want your music to be repeated, so you
-have to instruct her: a special bar symbol can be entered by the
-code(\bar) command followed by a string that signifies the bar symbol
-that you want. Then comes a semicolon to separate the string from the
-rest of the notes, just like with code(\key) and code(\time).
+) The end of the repeated music. LilyPond will typset a repeat bar.
verb(
cis'4 [b8 cis] a4 |
) COMMENT(
chords. You do this by expressing in mudela simultaneous music,
i.e., notes that are to be played concurrently.
+subsect(Where the chords have no names)
In Mudela you can form simultaneous music by enclosing notes in
pointed parentheses, bind(i.e.)bind(langle())bind(and)rangle(). ASCII
doesn't really have these delimiters, so Mudela uses the larger-than
[Chords and relative mode]
+subsect(Chords with names)
+
+In the previous section we have been talking more about 'stacked notes'
+rather than 'chords'.
+If you need to enter a lot of chords that have proper names, you can use
+the code(\chords) mode as an alternative:
+COMMENT(
+)mudela(verbatim,fragment,center)(
+ \chords\transpose c''{ c1 d e }
+)
+COMMENT( URG?
+ \chords\relative c''{ c1 d e }
+)
+
+subsect(Names with chords)
+
+A more common problem is the typesetting of chord names. LilyPond has
+a special kind of staff for this, the code(ChordNames) staff.
+The code(ChordNames) staff accepts music just as a normal staff,
+but typesets only the name of each chord:
+COMMENT(
+
+)mudela(verbatim,center)(
+\score{
+ \type ChordNames {
+ \chords
+ { c1 d-min e-maj5+.9 }
+ \notes\relative c
+ { <c1 es g> }
+ }
+ \paper{
+ linewidth=-1.0;
+ }
+}
+) Because the ChordNames staff accepts normal music, it can be transposed,
+and you may enter it any way you like, either as chords or as notes.
sect(Adding nuances: articulation and dynamics)
The only information that you need to enter is the
tempo (Unfortunately, at this time, this the only thing that can be
tuned.). The syntax for the tempo is code(\tempo )var(duration) =
-var(beatsperminute);), for example: COMMENT(
-
+var(beatsperminute);, for example: COMMENT(
)verb(
\score {
}
)
-Don't try to switch staffs when you are in the middle of a slur or
-beam, though: the spanners won't switch along.
+If you want to switch staffs you are in the middle of a slur or a
+beam, you should take special precautions. In the paper block,
+you must tell how far the staffs will be apart:
+mudela(verbatim,center)(
+\score{
+ \type GrandStaff <
+ \type Staff=one \notes{ s2 }
+ \type Staff=two \notes\relative c{
+ \time 4/8;
+ \clef "bass";
+ \stemup [c8( e
+ \translator Staff=one \stemup
+ g )c]
+ }
+ >
+ \paper {
+ linewidth=-1.0;
+ % slur damping gets confused
+ slur_slope_damping = 100.0;
+ \translator{
+ % we're using a grand staff
+ \GrandStaffContext
+ minVerticalAlign = 3.0*\staffheight;
+ maxVerticalAlign = 3.0*\staffheight;
+ }
+ }
+}
+)
+as LilyPond cannot determine the interstaff distance.
sect(Tuplets)
sect(Repeats)
-[todo]
+A repeated piece of music can consist of two parts: one part to be
+repeated, and optionally, a list of alternative endings:
+COMMENT(
+)mudela(verbatim,fragment,center)(
+ \relative c'{
+ \time 2/4;
+ g' a
+ \repeat 2 { b c }
+ \alternative {
+ { d c } { d e }
+ }
+ f g
+ }
+) The number code(repeat-count) defines how many times the piece should be
+played. You may leave out the code(\alternative) part. There must not
+be more alternative endings than the code(repeat-count).
+
+A somewhat less intuitive form may be needed for lyrics, when there are
+a couple alternatives, but nothing is repeated. The code(\repeat) command
+must be present, but it may specify an empty music list:
+COMMENT(
+)mudela(verbatim,fragment,center)(
+ \type Lyrics \lyrics {
+ \repeat 2 { }
+ \alternative <
+ { Let's not sing
+ this twice }
+ { Rather sing
+ this in- stead }
+ >
+ }
+)
+
+++ /dev/null
-Features you cannot find in the doco as working, should be mentioned
-here.
-
-This is an assorted collection of stuff that will be done, might be
-done, or is an idea that I want to think about
-
-Most of the items are marked in the code as well, with full explanation.
-grep for TODO and ugh/ugr/urg
-
-*In a piece such as the Zipoli piece in mutopia/... there is a stray
-`8' over every bar line when processed by LilyPond 1.1.25.
-
-TODO before 1.2
-
- * junk Text_def, use G_text_item in stead.
-
- * junk Script_def
-
- * fix partial measures in meaningful way.
-
- * fix AFM for BlueSky AFM files.
-
- * working notehead style.
-
- * add scripts to bars eg. |^"bla"
-
- * relative mode for mi2mu
-
- * uniformise recent feta contributions.
- - use SCM and Molecules for {accordeon stuff, }
- - bigger and fatter 4/4 C
-
- * make a SMOB of Atom and Molecule
-
- * use kerning for dynamics.
-
- * sort out directory stuff.
- - --prefix option?
- - -I option per filetype?
- - kpathsea?
-
-**************
-I also found a few bugs:
-
-* The examples in input/test/bar-scripts.ly and score-bar-scripts.ly
- don't work. The problem seems to be that you can't define a
- a score identifier and then use it in the \score block.
-
-
- - make separate MF chars for endings of ledger lines, and calc rest of lines.
-
- * support_l_arr_ empty in staff-margin's G_staff_side_item
-
-
-************
-
-How can I specify a chord whose duration is longer than a whole note?
-
- \type ChordNames { \chord{ A1*2-min } }
-
-gives me a parse error. And \times doesn't work either. I can't use
-a spacer note. So it seems to be impossible to have long chords of
-general length. Of course, in the example above I can use \breve.
-But what if I want a chord that lasts for 3 whole notes? Or what
-about 2.5 whole notes? Is there a mechanism for getting this kind of
-length?
-
-
-Why does my second extender request get junked in the following:
-
-\score{
-< \notes \relative c''{
- a4()b()c()d c()d()b()a }
- \type Lyrics \lyrics {
- foo1 __ bar2. __ _4 }
-> }
-
-It seems that \cr and \decr don't work any more.
-
-\score{
- \notes{
- a \cr b \rc c }
- \paper{linewidth=-1.;}
-}
-
-Gives me
-
-qq.ly:3:9: warning: can't find (de)crescendo to end:
- a \cr
- b \rc c }
-
-
-
-Use of semicolons is still rather confusing. They are obligatory
-after some types of assignments and illegal after others.
-
- \property foo=bar illegal
- foo = 3 at top level illegal
- foo = 3 inside \paper obligatory
- foo = \notes{ ...} top level illegal
- foo = \translator{ } in \paper obligatory
-
-As far as I can tell, the sole accomplishment of this syntactic
-irregularity is to keep the user as confused as possible.
-
-
-I was trying to get interstaff beams to work and did this:
-
-\score{
-\type GrandStaff <
-\type Staff=one \notes\relative c'{
- \stemup
- [c8 c \translator Staff=two \stemup c c]
- \translator Staff=one
- \stemdown
- [ b8 \translator Staff=two a8]
- \translator Staff=one
- c4
- }
-\type Staff=two \notes{ \clef bass; s1 }
->
-\paper{
- \translator{
- \GrandStaffContext
- minVerticalAlign = 3.0*\staffheight;
- maxVerticalAlign = 3.0*\staffheight;
- }
- linewidth = -1.;
-}
-}
-
-The beams are at the right angle, but they aren't in the right place.
-
-
-
-*******************
-
-
- * fractional chord durs.
-
- * hang Item on Spanner
-
- * remove Interval dim_ from Dimension_cache and rename the struct.
-
- * do --safe for PS output?
-
- * convert-mudela --output
-
- * Staff_margin (with a partial measure.)
-
- * fix "I've been drinking too much"
-
- * fix pletvisibility properties:
- - bracket on/off/no-bracket-when-beam
- - num on/off/no-num-when-beam
-
- * fix: standchen.
-
- * junk backlinks?
-
- * junk text{sharp,flat,etc}
-
- * fix convert-mudela manpage
-
- * decimal point in \paper {}
-
- *{ \voiceone <a'4.*2/3 d''4.*2/3 fis''4.*2/3> [g''8 fis'' e''] d''4 |}
- and=20
- { \voicetwo d'4 d'2.*2/3 } spacing
-
- * tied notes for MIDI
-
- * sharp /flat on trills (in MIDI ??)
-
- * scm-ify \property values.
-
- * move class Lookup {} into scm
-
-BUGS:
-
- * collisions/voices \voiceone \voicetwo are broken; see
- input/praeludium-fuga-E.ly
- mutopia/J.S.Bach/wtk1-fugue2.ly
-
- * fix: text on rests: rediculous dims
-
- * ly2dvi
- - bottomnote for ly2dvi
- - deps for ly2dvi
-
- * fix midi output:
- - default duration? duration must be not entered
- explicitely on first note.
-
- * turn slope-damping on/off
-
- * c4 \! \> c4
-
- * tremolo stuff
-
- * gallina barlines.
-
- * fix height of / collisions with lyrics (chords),
- see input/test/vertical-text.ly; input/test/repeat.ly
-
- * latex bla.tex broken (titles / \lilyfooter stuff?)
-
- * check/set minimum slur/tie length
-
- * msgfmt -o check?
-
- * \breathmark TeX macro
-
- * catch GUILE errors?
-
- * add new glyphs to font.ly
-
- * formatting of input stuff.
-
- * \notes{ a \< b \cr } vs \notes{ a \< b \! }
-
- * if possible, it might be nice for a warning to appear if someone does
- \translator with no name and without assigning it to an
- identifier.
-
- * space after bars?
-
- * 'hinterfleisch' before bar (e.g. wtk1-fugue2)?
-
- * \type Voice \times 2/3 { [c8 c16 c16 c16 c16] }
-
- * fix singleStaffBracket
-
- * repeat bars: need distance after ":|" and before "|:"
-
- Summary of minor spelling irregularities:
- - capitalization/use of underscores in property names
-
- * fix SkipBars -> skipBars
-
- * \shape 1st dim skipped?
-
- * fix marks/barnumbers/marginal notes
-
- * broken scripts:
- lbheel = \script { "bheel" 0 0 -1 0 0 }
- rbheel = \script { "bheel" 0 0 1 0 0 }
- lbtoe = \script { "btoe" 0 0 -1 0 0 }
- rbtoe = \script { "btoe" 0 0 1 0 0 }
- lfheel = \script { "fheel" 0 0 -1 0 0 }
- rfheel = \script { "fheel" 0 0 1 0 0 }
- lftoe = \script { "ftoe" 0 0 -1 0 0 }
- rftoe = \script { "ftoe" 0 0 1 0 0 }
-
- and also
-
- portato= \script { "portato" 0 -1 0 1 0 }
-
-STUFF
- * check out legal/(c) matters for scores.
-
- * check out GCC signatures?
-
- * Align_element::padding ?
-
- * uniformise property names...
- - ydirection <-> yDirection
- - rather allow '_' in identifiers first (i.e. junk ^ and _),
- and do y_direction?
- - typo checks on property names?
-
- * use streambufs and iostream
- to provide IO handling for TeX stream, mudela stream, data-file.
-
- * seriously buffer TeX output (do profile of writing .5 mb TeX file.)
-
- * strip EXEs before installing
-
- * zip target for binary windows dist (JBR)
-
- * junking \skip req in lyrics
-
- * Language:
- - \type -> \context ?
- - \translator -> ?
- - fix \partial
- - \bla {} vs \bla ;
- - mix engraver hacking with music ?
- - \once\property KEY = VAL
- - \addtranslator, \removetranslator
- - junk ^ and _ for scripts
- - junk _ for lyrics.
- - abstract grammar.
-
- * percussion note heads
-
- * mi2mu empty staffs.
-
- * horizontal centering of dynamics
-
- * \font\fontA=feta20.afm (.afm?)
-
- * gzip RH manpage
-
- * stable make/config stuff
-
- * $DEPENDENCIES_OUTPUT support
-
- * Xdvi zooming ?! Try to understand GS garbage collection.
- gs: Error: /undefined in draw_beam
- gs: Operand stack:
-
- * fix vertical alignment and stafflines
-
- * GrandStaff needs more work -- I want a single word
- `harpsichord' to the left of the grandstaff, not one on each
- stave. (Organ staff -- with separate pedal -- but common
- properties may be something to think about. Of course for
- organ you want to be able to give stop indications on the way
- through, so the \property Voice.Instrument would be a stop,
- and \property GrandStaff.instrument would be PipeOrgan...)
-
- * revise the Score_priority_align_engraver concept. It sucks.
-
- * make new VoiceOne, VoiceTwo, VoiceThree contexts with
-ydirection and hshift preset
-
- * *.yo: fix pod manpage layout legacy
-
- * text-items clash with stems/beams
-
- * --include, -I option for ly2dvi (pass on to lily)
-
- * fix placement of beam-less abbrev
-
- * \meter 3/4;
- <{\voiceone cis4. cis8 cis4 | cis4 cis cis | r1 }
- {\voicetwo cis,4 r r | r2. | r1 }> |
- }
-
- * try to use template<Type> iso MACRO(Type)
-
- - NEWS: ... Musical_pitch (analogous to Duration and Rhythmic_req)
- think about, analogous to pitch:
- * { a4 a16 } c <-- duration of c?
- * < a4 b8 > c <-- duration of c?
-
- * \tempo 4. = 90;
-
- * fix audio-items (don't use (input) requests, but copy data)
-
- * make sure all ex's have a mudela-version
-
- * do rest-collisions for Multi_measure_rests as well.
-
- * split error/warning in error/warning/non_fatal_error
-
- * add a Duration_convert member to Duration_iter to set parameters.
- Junk global duration settings.
-
- * minimum length second part broken tie
-
- * en-,discouraged linebreaking:
- - handle DISALLOW < penalty > FORCE
- - discourage breaking of slurs
-
- * fix variable define/lookup parser global<->paper
-
- * fix title/instrument placements; see input/test/title.ly
-
- * <\voiceone c4. \voicetwo c4>
-
- * add full cello suites to web site (kom op, Maarten!)
-
- * Rethink Time_description
- * \cadenza , \meter, \grouping should all be \properties
-
- * rename
- - measure -> bar
- - abbrev -> tremolo
- - abbreviation-beam -> (measured/unmeasured) tremolo
- - partial -> anacrouse
-
- * shared lib
-
- * robustify Beam (in case of no stems, 32nd notes)
-
- * decentralised spring factory
-
- * move paper vars into engraver properties
-
- * check for groff / troff/ nroff et
-
- * more intelligent file searching
-
- * make LilyPond RPM fully relocatable
-
- * disable spaces in TeX stuff
-
- * handle ^C for tmp/file creation.
-
- * dots & rest collisions.
-
- * documentation
- - introduction?
- - info?
- - LaTeX?
- - more manpages?
-
- * versioning for Feta
-
- * the warning about the negative slur/tie length appears twice
- which is irritating.
-
- * The `3' in the meter key is a one or two pixels too thin (at 600dpi)
- in the middle:
-
- * the bracket is ugly (wings are too parabolic, should be more circular)
-
- * better hshift (dots, distance, head dependent)
-
- * clefs (AG): The "8" should appear closer to the actual clef,
- touching it.
-
- * put errorlevel in Input class
-
- * junk nesting slurs
-
- * integrate midi-elts from mi2mu and lily?
-
-
-3RD PARTY BUGS:
-****************
-/*
-ICE
-*/
-signature S {
- int foo ();
-};
-
-signature V {
- S * s();
-};
-
-
-V*v();
-f ()
-{
- return v( )->foo ();
-}
-
-/*
-
- egcs-1.1
-
-foo.cc: In function `int f()':
-foo.cc:6: label `b' used but not defined
-*/
-void
-f ()
-{
- bool b;
- if (b && && b)
- ;
-}
-***************
-
- * make GCC warn about ctor that leaves member vars uninitialised.
-
- * GNU diff 2.7: diff -rN does not see a new directory with empty file
-
- * glibc 2.0:
-
- f = fopen ("/dev/null", "r")
- assert (feof (f))
-
-3RD PARTY PROJECTS:
-
- * GNU patch
- - 'double-fix' mode: ignore identical fix, rather than suggest
- to revert patch direction when (more or less? exactly) the same
- thing is fixed
-
-PROJECTS
-
- * Scripts:
- - fix position of bar number
- - stack scripts in chords:
- % fingering: footing:
- < a-4 c-2 g-1 > < c-\ltoe e-\lheel >
- - script-spacing
- - slur parts as a script
- - stack parameterised scripts for fingering and footing:
-
- * convert-mudela:
- - automatically add a \version if not present.
- - better parsing
- - make smarter
- - convert-mudela -e empty.ly
-
- * emacs mudela-mode
- - should handle block comments too.
- - handle lexer modes (\header, \melodic, \lyric) etc.
- - indentation
- - notenames?
- - fontlock: \melodic \melodic
-
- * use properties for:
- - plet?
- - Staff_sym size
- - default tempo.
- - font size
- - bartypes (get rid of derived Span_bar_engravers)
- - cadenza mode?
-
- * page handling:
- - PS output
- - optimal pagebreaking.
-
- * Unicode support? -> man 7 unicode
- - 16 bit Strings
- - -u switch
- - detect of 16/8 bit files
- - examples to go with it.
-
- * Spring_spacer:
- - write a faster Spring_spacer (without matrices if possible)
- - relate energybound to linelen unitspace fontsize etc.
- - used fixed point fp?
-
- * \header
- - output header info to MIDI too.
-
- * a musical dictionary. See Documentation/vocabulary-*, other
- languages:
- - explanations
- - italian
- - german
- - dutch
- - swedish
- .. ?
-
- * chords
- - guitar chords (fret diagrams)
- - other chord name styles (american(?) style)
- - basso continuo
- - MIDI output?
-
- * Debug logs:
- - derive lily_stream, Dstream, texstream from ostream?
- - indentable stream as baseclass for TeX stream, lily stream, Dstream.
- - use dstream feature in mi2mu
- - integrate IO checking into stream class
-
- * input converters
- - NIFF?
- - ABC?
- - SMDL?
-
- * add to MIDI output:
- - tempo change
- - ornaments (and trills?)
- - repeat/volta
- - slurs
- - accents
- - dynamics
- - account for rhythmic position in measure
- - etc.
-
- * grace notes
- - make separate class for Grace_*_engravers
- (which is at Voice_gravs level)
- - make encapsulated spacing problems.
-
- * accidentals per Voice_group
-
- * Output class, handles : (smallish)
- - help text /(c) notice?
- - version line
- - warning /errors/progress
- - abort on error/warning; exit status
- - quiet/ignore-version options
- - logfile output
-
- * elaborate Staff_side baseclass:
- - scripts
- - text
- - slur start/end
-
- * PS
- - speed up PS code.
- - PS lines to .eps files
- - write custom prolog
-
- * Output an output format independent (ofi) typeset file; and
- make ofi2 TeX, MusiXTex, Display PostScript, PostScript,
- Ascii... interpreters. (difficult)
-
- - NIFF ?
- - Common Music Notation
- - PostScript output (esp. Beams, Slurs, etc)
- - Move all Score_elems, into libmutype.a
- - SGML
-
- * Documentation
- - Doc (C) stuff of sheet music
- - a better format? SGML? TeX? Info?
- - a better tutorial
-
- * more spanners (smallish)
- - Glissando
- - trill
-
- * Rewrite Stem, Beam and Rhythmic_grouping (hairy)
- - [c8. c32 c32]
- - doc on Rhythmic_grouping
- - general shaving on Beam and Stem
- - use plet grouping
- - separate visual from rhythmic info even more
- - beams over bars
-
- * lines:
- - Ledger lines, should be separate item: Ledger_lines, Ledger_lines
- - set different line sizes / thicknesses
- - beam stem showthrough, inter beam sizes (french vs german style)
-
- * Collisions
- - left/right note balls should be handled by Collision:
- < \multi 2; { \stem 1; <b c> } { <f as b> } >
-
- * Keys:
- - merge key{item} & localkey{item}?
- - spacing, national styles?
-
- * Support for TAB
- - redo Notehead to allow digits as heads
- - add a \tablature {} lexer mode for easy entering
-
- * should adjust stemlength for flag number.
-
- * breaking:
- - caching breakpoints
- - saving them
- - specify number of lines
-
-INPUTLANGUAGE
-
- * c4 4 4 4 for c4 c4 c4 c4?
-
- * neatly (and readably) expressing concurrent
- voices
-
- * <c f a>4 ?
-
- * Viola mode?
-
- @c c g e g
- for
- c g es g,
-
- @A c g e g
- for
- cis gis e gis
-
- * relative mode for pitch entering
-
- * configure pitch_byte
-
- * rest name configurable
-
-SMALLISH PROJECTS
-
- * limit memory usage; the full coriolan takes up too much resources.
-
- * fix confusing naming in Engraver vs Engraver_group_engraver (context)
-
- * progress when creating MIDI elts.
-
- * A range for context errors (eg. mark both { and }. )
-
- * lyric in staff (sharpsharp in staff, text below)
-
- * half sharps/flats
-
- * write Dynamic_line (to group dynamics horizontally)
-
- * use Real for all y positions.
- - use translate_axis( .. ,Y_AXIS) iso separate variables.
-
- * half-sharps, half-flats
-
- * adaptive accidental spacing.
-
- * handle EOF graciously in error messages.
-
- * declare notenametab?
-
- * midi esp.: use I32 iso int where 32 bits are needed (or assumed...)
-
- * stafftypes: voice names/ instrument names.
-
- * lily \tempo
-
- * C meter iso 4/4, idem for alla breve, etc.
-
- * textspanner: center position
-
- * % toe to bheel four to five
- % ^_u 4_5
- % -
- % --|x-- --|x--
- % --|--- --|---
- % --|--- --|---
- (where "to" is a tiny bow)
-
- * auxilliary file for caching info.
-
- * Text_crescendo
-
- * clean solution for staffsize in items.
-
- * revise calcideal
-
-IDEAS
-
- * Output data structures of Mudela in XML/SGML.
-
- * create libmudela, or liblily_frontend
-
- * move MIDI stuff (including Quantization) to a ANSI C libmidi library.
-
- * Spacing_request for manually adjusting spacing
-
- * caching breakpoints
-
- * used fixedpoint arithmetic for min. energy.
-
- * move towards incremental algorithms.
-
- * far fetched language ideas
- - design meta-language like TeX and Metafont
- - programming/macros input
-
- * versioning stuff (cvt mudela, mudela, etc.)
-
- * Klavarskribo?
-
- * dynamic loading of engravers?
-
-SMOBS:
-
-****************************************
-Han-Wen Nienhuys <hanwen@cs.uu.nl> writes:
-
-> mcmanus@IDT.NET writes:
-> > > I want different C++ objects (with scheme embedded) to be linked by
-> > > C++ pointers. I want to access these other objects from the Scheme
-> > > code, and I want access to these pointers from C++.
-> >
-> > You can do this with a combination of smob's and primitive functions,
-> > though it may not be be exactly what you wanted. You would have one
-> > smob for each class in your application, and then you would write a
-> > primitive function that would return the objects that are linked to a
-> > base object.
->
-> And the smob and the C++ class are interlinked? Like
->
-> class Foo_class {
-> Foo_smob *smob_ptr_;
-> }
->
-> struct Foo_smob {
-> Foo_class *class_ptr_
-> }
-
-Usually you can get away without having this interlinked structure.
-One piece of information you need when exporting objects to scheme is
-the smob tag for your class. You might store this value (a long) into
-a class static variable, or a file static variable. I'll use a class
-static variable in this example.
-
-I typically use code that works like this (untested code ahead):
-
-class Foo_class {
- static long *Foo_smob_tag;
- SCM obj; // representation as a scheme object, description comes later
-}
-
-// call this once on startup
-void init_Foo_class {
- static scm_smobfuns type_rec;
-
- type_rec.mark = foo_mark;
- type_rec.free = foo_free;
- type_rec.print = foo_display;
- type_rec.equalp = 0;
- Foo_class::Foo_smob_tag = new int(scm_new_smob(type_rec));
-}
-
-When you want to export an object to scheme, you put a pointer to the
-object itself in the cdr of the cell, and the tag in the car of the
-cell. The code looks like this:
-
-// Is this a Foo?
-static int
-foo_p(SCM obj)
-{
- return(SCM_NIMP(obj) && SCM_CAR(obj) == Foo_class::Foo_smob_tag);
-}
-
-// given a Scheme representation, return, a C++ representation
-static Foo_class *
-foo_unbox(SCM obj)
-{
- return((Foo_class*)SCM_CDR(obj));
-}
-
-// the SCM representation of the object is stored inside itself
-// this will become useful when destructor gets called
-static SCM
-foo_box(Foo_class *foo)
-{
- SCM_DEFER_INTS;
- SCM_NEWCELL(foo->obj);
- SCM_SETCAR(foo->obj, Foo_class::Foo_smob_tag);
- SCM_SETCDR(foo->obj, (SCM)foo);
- SCM_ALLOW_INTS;
- return foo->obj;
-}
-
-> C++ determines life time, so what is the strategy?
-
-What happens now when the destructor gets called? Lets set the cdr to
-NULL, and then check for that in all of the primitive functions that
-use your smob. We'll call this notion 'live'; a scheme object is
-'live' if the C++ representation still exists, it's dead if the C++
-object is gone. You can still have references to dead objects in
-scheme code; it's just an error to use them. This idea is stolen from
-Emacs's handling of buffers ('buffer-live-p' and friends).
-
-Add another function, foo_live_p:
-
-static int
-foo_live_p(SCM obj)
-{
- return(foo_p(obj) && SCM_CDR(obj) != NULL);
-}
-
-In you destructor, you need to do:
-
-~Foo_class()
-{
- SCM_CDR(this->obj, NULL);
-}
-
-When writing new primitives, now just check foo_live_p().
-
-I hope the above helps,
-
--russ
-
-
---
-"Even if you are on the right track, you'll get run over
-if you just sit there."
- --Will Rogers (1879-1935)
-
-***************************
-
-> I am still muddling along with integrating GUILE in LilyPond, and I
-> have a question. I want to replace an existing C++ implementation of
-> identifier tables by GUILE's code. I've managed to replace
->
-> Hash_table<String,Identifier*>
->
-> by
->
-> Hash_table<SCM, Identifier*>
->
-> and use interning and GUILE symbols for doing the identifier lookup.
-> But I'd like to use GUILE's hash tables as well, and that's were my
-> question comes in: is there an interface that allows me to iterate
-> through the entries of a GUILE hash table?
-
-I use the following, which should definitely be provided somewhere
-in guile, but isn't, AFAIK:
-
-(define (hash-table-for-each fn ht)
- (do ((i 0 (+ 1 i)))
- ((= i (vector-length ht)))
- (do ((alist (vector-ref ht i) (cdr alist)))
- ((null? alist) #t)
- (fn (car (car alist)) (cdr (car alist))))))
-
-(define (hash-table-map fn ht)
- (do ((i 0 (+ 1 i))
- (ret-ls '()))
- ((= i (vector-length ht)) (reverse ret-ls))
- (do ((alist (vector-ref ht i) (cdr alist)))
- ((null? alist) #t)
- (set! ret-ls (cons (fn (car (car alist)) (cdr (car alist))) ret-ls)))))
-
-If you want a C version, you can run the above code through hobbit, or
-tranlate it to C by hand.
-
--russ
-
-
---
-"Whenever you find yourself on the side of the majority, it is time to
-pause and reflect."
- -- Mark Twain
-***********************
projects / lilypond.git / commitdiff