Merge branch 'lilypond/translation' of ssh://jomand@git.sv.gnu.org/srv/git/lilypond

[lilypond.git] / Documentation / devel / doc-work.itexi

@c -*- coding: us-ascii; mode: texinfo; -*-
@node Documentation work
@chapter Documentation work

@menu
* Introduction to documentation work::  
* Texinfo crash course::        
* Documentation policy::        
* Tips for writing docs::       
* Updating docs with convert-ly::  
* Translating the documentation::  
@end menu


@node Introduction to documentation work
@section Introduction to documentation work

Our documentation tries to adhere to our @ref{Documentation
policy}.  This policy contains a few items which may seem odd.
One policy in particular is often questioned by potential
contributors: we do not repeat material in the Notation Reference,
and instead provide links to the @qq{definitive} presentation of
that information.  Some people point out, with good reason, that
this makes the documentation harder to read.  If we repeated
certain information in relevant places, readers would be less
likely to miss that information.

That reasoning is sound, but we have two counter-arguments.
First, the Notation Reference -- one of @emph{five} manuals for
users to read -- is already over 500 pages long.  If we repeated
material, we could easily exceed 1000 pages!  Second, and much
more importantly, LilyPond is an evolving project.  New features
are added, bugs are fixed, and bugs are discovered and documented.
If features are discussed in multiple places, the documentation
team must find every instance.  Since the manual is so large, it
is impossible for one person to have the location of every piece
of information memorized, so any attempt to update the
documentation will invariably omit a few places.  This second
concern is not at all theoretical; the documentation used to be
plagued with inconsistent information.

If the documentation were targeted for a specific version -- say,
LilyPond 2.10.5 -- and we had unlimited resources to spend on
documentation, then we could avoid this second problem.  But since
LilyPond evolves (and that is a very good thing!), and since we
have quite limited resources, this policy remains in place.

A few other policies (such as not permitting the use of tweaks in
the main portion of NR 1+2) may also seem counter-intuitive, but
they also stem from attempting to find the most effective use of
limited documentation help.



@node Texinfo crash course
@section Texinfo crash course

The language is called texinfo; you can see its manual here:
@uref{http://www.gnu.org/software/texinfo/manual/texinfo/}

However, you don't need to read those docs.  The most important
thing to notice is that text is text.  If you see a mistake in the
text, you can fix it.  If you want to change the order of
something, you can cut-and-paste that stuff into a new location.

@warning{Rule of thumb: follow the examples in the existing docs.
You can learn most of what you need to know from this; if you want
to do anything fancy, discuss it on @code{lilypond-devel} first.}


@subsection Sectioning commands

Most of the manual operates at the

@example
        @@node Foo
        @@subsubsection Foo
@end example

@noindent
level.  Sections are created with

@example
        @@node Foo
        @@subsection Foo
@end example

@itemize
@item Please leave two blank lines above a @@node; this makes it
easier to find sections in texinfo.

@item Sectioning commands (@@node and @@section) must not appear
inside an @@ignore.  Separate those commands with a space, ie @@n
ode.

@end itemize



@subsection LilyPond formatting

@itemize

@item Use two spaces for indentation in lilypond examples.  (no
tabs)

@item All text strings should be prefaced with #.  LilyPond does
not strictly require this, but it is helpful to get users
accustomed to this scheme construct.  ie @code{\set
Staff.instrumentName = #"cello"}

@item All engravers should have double-quotes around them:

@example
    \consists "Spans_arpeggio_engraver"
@end example

Again, LilyPond does not strictly require this, but it is a useful
standard to follow.

@item Examples should end with a complete bar if possible.

@item If possible, only write one bar per line.  The notes on each
line should be an independent line -- tweaks should occur on their
own line if possible.  Bad:

@example
\override textscript #'padding = #3 c1^"hi"
@end example

Good:

@example
\override textscript #'padding = #3
c1^"hi"
@end example

@item Most LilyPond input should be produced with:

@example
@@lilypond[verbatim,quote,relative=2]
@end example

@noindent
or

@example
@@lilypond[verbatim,quote,relative=1]
@end example

If you want to use \layout@{@} or define variables, use

@example
@@lilypond[verbatim,quote]
@end example

In rare cases, other options may be used (or omitted), but ask first.

@item
Inspirational headwords are produced with

@example
@@lilypondfile[quote,ragged-right,line-width=16\cm,staffsize=16]
@{pitches-headword.ly@}
@end example

@item LSR snippets are linked with

@example
@@lilypondfile[verbatim,lilyquote,ragged-right,texidoc,doctitle]
@{filename.ly@}
@end example

@noindent
excepted in Templates, where `doctitle' may be omitted.

@item Avoid long stretches of input code.  Noone is going to read
them in print.  Please create a smaller example.  (the smaller
example does not need to be minimal, however)

@item Specify durations for at least the first note of every bar.

@item If possible, end with a complete bar.

@item Comments should go on their own line, and be placed before
the line(s) to which they refer.

@item Add extra spaces around @{ @} marks; ie

@example
not:          \chordmode @{c e g@}
but instead:  \chordmode @{ c e g @}
@end example

@item If you only have one bar per line, omit bar checks.  If you
put more than one bar per line (not recommended), then include bar
checks.

@item If you want to work on an example outside of the manual (for
easier/faster processing), use this header:

@example
\paper @{
  #(define dump-extents #t)
  indent = 0\mm
  line-width = 160\mm - 2.0 * 0.4\in
  ragged-right = ##t
  force-assignment = #""
  line-width = #(- line-width (* mm  3.000000))
@}

\layout @{
@}
@end example

You may not change any of these values.  If you are making an
example demonstrating special \paper@{@} values, contact the
Documentation Editor.

@end itemize


@subsection Text formatting

@itemize

@item
* Lines should be less than 72 characters long.  (I personally
  recommend writing with 66-char lines, but don't bother modifying
  existing material.)

@item
* Do not use tabs.

@item
* Do not use spaces at the beginning of a line (except in @@example
  or @@verbatim environments), and do not use more than a single
  space between words.  `makeinfo' copies the input lines verbatim
  without removing those spaces.

@item
* Use two spaces after a period.

@item
* In examples of syntax, use @@var@{musicexpr@} for a music
  expression.

@item
* Don't use @@rinternals@{@} in the main text.  If you're tempted to
  do so, you're probably getting too close to "talking through the
  code".  If you really want to refer to a context, use @@code@{@} in
  the main text and @@rinternals@{@} in the @@seealso.

@item
* Variables or numbers which consist of a single character
  (probably followed by a punctuation mark) should be tied
  properly, either to the previous or the next word.  Example:

      The variable@@tie@{@}@@var@{a@} ...

@item
* To get consistent indentation in the DVI output it is better to
  avoid the @@verbatim environment.  Use the @@example environment
  instead if possible, but without extraneous indentation.  For
  example, this

    @@example
      foo @{
        bar
      @}
    @@end example

  should be replaced with

    @@example
    foo @{
      bar
    @}
    @@end example

  where `@@example' starts the line (without leading spaces).

@item
* Do not compress the input vertically; this is, do not use

    Beginning of logical unit
    @@example
    ...
    @@end example
    continuation of logical unit

  but

    Beginning of logical unit

    @@example
    ...
    @@end example

    @@noindent
    continuation of logical unit

  This makes it easier to avoid forgetting the `@@noindent'.  Only
  use @@noindent if the material is discussing the same material;
  new material should simply begin without anything special on the
  line above it.

@item
* in @@itemize use @@item on a separate line like this:
  @@itemize
  @@item
  Foo

  @@item
  Bar

  Do not use @@itemize @@bullet.

@item
* To get LilyPond version, use @@version@{@} (this does not work inside
  LilyPond snippets).  If you write "@@version@{@}" (enclosed with
  quotes), or generally if @@version@{@} is not followed by a space,
  enclose it with

  @@w@{ ... @}

  e.g.

  @@w@{"@@version@{@}"@}

  to prevent an ugly line break in PDF output.
@end itemize


@subsection Syntax survey

@itemize
@item
@@c - single line comments
  "@@c NOTE:" is a comment which should remain in the final
  version.  (gp only command ;)
@item
@@ignore ... @@end ignore - multi-line comment

@item
@@cindex - General index. Please add as many as you can.  Don't
  capitalize the first word.
@item
@@funindex - is for a \lilycommand.

@item
@@example ... @@end ignore - example text that should be set as a
  blockquote.  Any @{@} must be escaped with @@@{ @}@@
@item
@@itemize @@item A @@item B ... @@end itemize - for bulleted lists.
  Do not compress vertically like this.

@item
@@code@{@} - typeset in a tt-font. Use for actual lilypond code or
  property/context names.  If the name contains a space, wrap
  the entire thing inside @@w@{@@code@{  @}@}.
@item
@@notation@{@} - refers to pieces of notation, e.g.
  "@@notation@{cres.@}".  Also use to specific lyrics ("the
  @@notation@{A - men@} is centered").  Only use once per subsection
  per term.
@item
@@q@{@} - Single quotes. Used for `vague' terms.
@item
@@qq@{@} - Double quotes.  Used for actual quotes ("he said") or for
  introducing special input modes.

@item
@@tie@{@} - Variables or numbers which consist of a single character
  (probably followed by a punctuation mark) should be tied
  properly, either to the previous or the next word.  Example:
    "The letter@@tie@{@}@@q@{I@} is skipped"

@item
@@var - Use for variables.
@item
@@warning@{@} - produces a "Note: " box. Use for important messages.

@item
@@bs - Generates a backslash inside @@warning.
    Any `\' used inside @@warning (and @@q or @@qq) must be written as `@@bs@{@}' 
    (texinfo would also allow \\, but this breaks with PDF output).

@end itemize



@subsection Other text concerns

@itemize

@item
* References must occur at the end of a sentence, for more
  information see @@ref@{the texinfo manual@}.  Ideally this should
  also be the final sentence of a paragraph, but this is not
  required.  Any link in a doc section must be duplicated in the
  @@seealso section at the bottom.

@item
* Introducing examples must be done with
     . (ie finish the previous sentence/paragaph)
     : (ie `in this example:')
     , (ie `may add foo with the blah construct,')
  The old "sentence runs directly into the example" method is not
  allowed any more.

@item
* Abbrevs in caps, e.g., HTML, DVI, MIDI, etc.

@item
* Colon usage

  1. To introduce lists
  2. When beginning a quote: "So, he said,..."
     This usage is rarer.  Americans often just use a comma.
  3. When adding a defining example at the end of a sentence.

@item
* Non-ASCII characters which are in utf-8 should be directly used;
  this is, don't say `Ba@@ss@{@}tuba' but `Baßtuba'.  This ensures that
  all such characters appear in all output formats.

@end itemize




@node Documentation policy
@section Documentation policy


@subsection Books

There are four parts to the documentation: the Learning Manual,
the Notation Reference, the Program Reference, and the Music
Glossary.

@itemize

@item
* Learning Manual:
  The LM is written in a tutorial style which introduces the most
  important concepts, structure and syntax of the elements of a
  LilyPond score in a carefully graded sequence of steps.
  Explanations of all musical concepts used in the Manual can be
  found in the Music Glossary, and readers are assumed to have no
  prior knowledge of LilyPond.  The objective is to take readers to
  a level where the Notation Reference can be understood and
  employed to both adapt the templates in the Appendix to their
  needs and to begin to construct their own scores.  Commonly used
  tweaks are introduced and explained.  Examples are provided
  throughout which, while being focussed on the topic being
  introduced, are long enough to seem real in order to retain the
  readers' interest.  Each example builds on the previous material,
  and comments are used liberally.  Every new aspect is thoroughly
  explained before it is used.

Users are encouraged to read the complete Learning Manual from
start-to-finish.


@item
* Notation Reference: a (hopefully complete) description of
  LilyPond input notation.  Some material from here may be
  duplicated in the Learning Manual (for teaching), but consider
  the NR to be the "definitive" description of each notation
  element, with the LM being an "extra".  The goal is _not_ to
  provide a step-by-step learning environment -- do not avoid
  using notation that has not be introduced previously in the
  NR  (for example, use \break if appropriate).  This section is
  written in formal technical writing style.

Avoid duplication.  Although users are not expected to read this
manual from start to finish, they should be familiar with the
material in the Learning Manual (particularly ``Fundamental
Concepts''), so do not repeat that material in each section of
this book.  Also watch out for common constructs, like ^ - _ for
directions -- those are explained in NR 3.  In NR 1, you can
write:
DYNAMICS may be manually placed above or below the
staff, see @@ref@{Controlling direction and placement@}.

Most tweaks should be added to LSR and not placed directly in the
.itely file.  In some cases, tweaks may be placed in the main
text, but ask about this first.

Finally, you should assume that users know what the notation
means; explaining musical concepts happens in the Music Glossary.


@item
* Application Usage: information about using the program lilypond
  with other programs (lilypond-book, operating systems, GUIs,
  convert-ly, etc).  This section is written in formal technical
  writing style.

Users are not expected to read this manual from start to finish.


@item
* Music Glossary: information about the music notation itself.
  Explanations and translations about notation terms go here.

Users are not expected to read this manual from start to finish.

@item
* Internals Reference: not really a documentation book, since it
  is automagically generated from the source, but this is its
  name.

@end itemize


@subsection Section organization

@itemize

@item The order of headings inside documentation sections should
be:

@example
main docs
@@predefined
@@endpredefined
@@snippets
@@seealso
@@knownissues
@end example

@item
* You _must_ include a @@seealso.  The order of items inside the
  @@seealso section is

    Music Glossary:
    @@rglos@{foo@},
    @@rglos@{bar@}.

    Learning Manual:
    @@rlearning@{baz@},
    @@rlearning@{foozle@}.

    Notation Reference:
    @@ruser@{faazle@},
    @@ruser@{boo@}.

    Application Usage:
    @@rprogram@{blah@}.

    Installed Files:
    @@file@{path/to/dir/blahz@}.

    Snippets: @@rlsr@{section@}.

    Internals Reference:
    @@rinternals@{fazzle@},
    @@rinternals@{booar@}.

      If there are multiple entries, separate them by commas
      but do not include an `and'.

      Always end with a period.

      Place each link on a new line as above; this makes it much
      easier to add or remove links.  In the output, they
      appear on a single line.

  ("Snippets" is REQUIRED; the others are optional)

  Any new concepts or links which require an explanation should go
  as a full sentence(s) in the main text.

  Don't insert an empty line between @@seealso and the first entry!
  Otherwise there is excessive vertical space in the PDF output.

@item
* To create links, use @@ref@{@} if the link is within the same
  manual.

@item
* @@predefined ... @@endpredefined is for commands in ly/*-init.ly
  FIXME?

@item
* Do not include any real info in second-level sections (ie 1.1
  Pitches).  A first-level section may have introductory material,
  but other than that all material goes into third-level sections
  (ie 1.1.1 Writing Pitches).

@end itemize


@subsection Checking cross-references

Cross-references between different manuals are heavily used in the
documentation, but they are not checked during compilation.  However,
if you compile the documentation, a script called check_texi_refs can
help you with checking and fixing these cross-references; for
information on usage, cd into a source tree where documentation has
been built, cd into Documentation and look for check-xrefs and
fix-xrefs targets in 'make help' output.  Note that you have to find
yourself the source files to fix cross-references in the generated
documentation such as the Internals Reference; e.g. you can grep
scm/ and lily/.


@subsection General writing

@itemize

@item
* Do not forget to create @@cindex entries for new sections of text.
  Enter commands with @@funindex, i.e.
    @@cindex pitches, writing in different octaves
    @@funindex \relative
  do not bother with the @@code@{@} (they are added automatically).  These
  items are added to both the command index and the unified index.

  Both index commands should go in front of the actual material.

  @@cindex entries should not be capitalized, ie
    @@cindex time signature
  is preferred.  (instead of `Time signature')   Only use capital
  letters for musical terms which demand them, like D.S. al Fine.

  For scheme functions, only include the final part, ie
    @@funindex modern-voice-cautionary
  and NOT
    @@funindex #(set-accidental-style modern-voice-cautionary)

@item
* Preferred terms:
    - in general, use the American spellings.  The internal
      lilypond property names use this spelling.
    - list of specific terms:
canceled
simultaenous    NOT concurrent
measure: the unit of music
bar line: the symbol delimiting a measure   NOT barline
note head   NOT notehead
chord construct   NOT chord (when referring to <>)

@end itemize


@subsection Technical writing style

@itemize

@item
* Do not refer to LilyPond in the text.  The reader knows what the
  manual is about.  If you do, capitalization is LilyPond.

@item
* If you explicitly refer to `lilypond' the program (or any other
  command to be executed), say `@@command@{lilypond@}'.

@item
* Do not explicitly refer to the reader/user.  There is no one
  else besides the reader and the writer.

@item
* Do not use abbreviations (don't, won't, etc.).  If you do, use a
  comma after it:

    blabla blabla, i.e., blabla blabla

@item
* Avoid fluff (``Notice that,'' ``as you can see,''
  ``Currently,'').

@item
* The use of the word `illegal' is inappropriate in most cases.
  Say `invalid' instead.

@end itemize


@node Tips for writing docs
@section Tips for writing docs

In the NR, I highly recommend working on one subsection at a time.
For each subsection,

- check the mundane formatting.  Are the headings (@@predefined,
  @@seealso, etc) in the right order?
- add any appropriate index entries.
- check the links in the @@seealso section -- links to music
  glossary, internal references, and other NR sections are the
  main concern.  Check for potential additions.
- move LSR-worthy material into LSR.  Add the snippet (or
  just send it to Valentin for adding), delete the material from
  the .itely file, and add a @@lilypondfile command.

- check the examples and descriptions.  Do they still work?
  *Do not* assume that the existing text is accurate/complete;
  some of the manual is highly out of date.
- is the material in the @@knownissues  still accurate?
- process anything on the TODO list on the GDP web site.
- can the examples be improved (made more explanatory), or is
  there any missing info?  (feel free to ask specific questions
  on -user; a couple of people claimed to be interesting in being
  "consultants" who would help with such questions)

In general, I favor short text explanations with good examples --
"an example is worth a thousand words".  When I worked on the
docs, I spent about half my time just working on those tiny
lilypond examples.  Making easily-understandable examples is much
harder than it looks.


TWEAKS

In general, any \set or \override commands should go in the
"select snippets" section, which means that they should go in LSR
and not the .itely file.  For some cases, the command obviously
belongs in the "main text" (ie not inside @@predefined or @@seealso
or whatever) -- instrument names are a good example of this.
  \set Staff.instrumentName = #"foo"
On the other side of this,
  \override Score.Hairpin #'after-line-breaking = ##t
clearly belongs in LSR.

I'm quite willing to discuss specific cases if you think that a
tweaks needs to be in the main text.  But items that can go into
LSR are easier to maintain, so I'd like to move as much as
possible into there.


It would be "nice" if you spent a lot of time crafting nice tweaks
for users... but my recommendation is *not* to do this.  There's a
lot of doc work to do without adding examples of tweaks.  Tweak
examples are trivial to add later -- they could be made by normal
users, or by you after GDP is over.

Basically, it's not something that needs to be done while I'm
around.  Remember that I'm gone in August at the latest; there's a
*lot* of doc work that should be done before then.  I strongly
recommend that you save all the tweaks until later.


FINAL

- when you think you're finished, let me know.  I'll spend a few
  minutes and send you a list of mistakes to fix.
  (there's a *lot* of details to cover; we'll probably spend a
  week going back and forth like this.  See earlier warning about
  hating me by the time you're done with a doc section :)
- I'll ask people on -user to review the Snippet list at this
  time; correcting things on the Snippet list is much easier than
  getting comments on the integrated snippets.
- when we're both satisfied with the section, we'll invite
  comments from -user.  Judging from my experience with Pitches,
  it will take between three and five weeks to keep on revising
  the "final" version.

I personally found it quite frustrating to still be fixing
problems in a doc section which I thought was "perfect" a whole
bloody *month* ago.  Don't get me wrong; it's great that we get so
many comments from -user.  :)   But just be aware that when you
think you're finally done with a section, you're actually only
halfway there.







@node Updating docs with convert-ly
@section Updating doc with convert-ly

cd into Documentation and run

@example
find . -name '*.itely' | xargs convert-ly -e
@end example

@noindent
(This also updates translated docs.)




@node Translating the documentation
@section Translating the documentation