report(CodingStyle - standards while programming for GNU
LilyPond)(Han-Wen Nienhuys and Jan Nieuwenhuizen)()()

nsect(DESCRIPTION)

We use these standards while doing programming for GNU LilyPond.  If
you do some hacking, we appreciate it if you would follow this rules,
but if you don't, we still like you.

Functions and methods do not return errorcodes.

quote(

A program should be light and agile, its subroutines
connected like a string of pearls.  The spirit and intent of
the program should be retained throughout.  There should be
neither too little nor too much, neither needless loops nor
useless variables, neither lack of structure nor overwhelming
rigidity.

A program should follow the 'Law of Least
Astonishment'.  What is this law?  It is simply that the
program should always respond to the user in the way that
astonishes him least.

A program, no matter how complex, should act as a
single unit.  The program should be directed by the logic
within rather than by outward appearances.

If the program fails in these requirements, it will be
in a state of disorder and confusion.  The only way to correct
this is to rewrite the program.

-- Geoffrey James, "The Tao of Programming"
)


nsubsect(LANGUAGES)

C++, /bin/sh and Python are preferred.  Perl is not.
Python code should use an indent of 8, using TAB characters.

nsubsect(FILES)

Definitions of classes that are only accessed via pointers
(*) or references (&) shall not be included as include files.

filenames

verb(
	".hh"	Include files
	".cc"	Implementation files
	".icc"	Inline definition files
	".tcc"	non inline Template defs
)

in emacs:

verb(
	(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))
)


The class Class_name_abbreviation is coded in file(class-name-abbr.*)


nsubsect(INDENTATION)

in emacs:

verb(
	(add-hook 'c++-mode-hook
		  '(lambda() (c-set-style "gnu")
		     )
		  )
)

If you like using font-lock, you can also add this to your file(.emacs):

verb(
	(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))
	       ))
)

nsubsect(CLASSES and TYPES:)

verb(
	This_is_a_class
)

nsubsect(MEMBERS)

verb(
	Class::member ()
	Type Class::member_type_
	Type Class::member_type ()
)

the code(type) is a Hungarian notation postfix for code(Type). See below

nsubsect(MACROS)

Macros should be written completely in uppercase

The code should not be compilable if proper macro declarations are not
included. 

Don't laugh. It took us a whole evening/night to figure out one of
these bugs, because we had a macro that looked like
code(DECLARE_VIRTUAL_FUNCTIONS ()). 

nsubsect(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.

nsubsect(COMMENTS)

The source is commented in the DOC++ style.  Check out doc++ at
lurl(http://www.zib.de/Visual/software/doc++/index.html)

verb(
	/*
		C style comments for multiline comments.
		They come before the thing to document.
		[...]
	*/


	/**
		short description.
		Long class documentation.
		(Hungarian postfix)

		TODO Fix boring_member ()
	*/
	class Class {
		/**
		  short description.
		  long description
		*/

		Data data_member_;


		/**
			short memo. long doco of member ()
			@param description of arguments
			@return Rettype
		*/
		Rettype member (Argtype);

		/// memo only
		boring_member () {
			data_member_ = 121; // ugh
		}
	};
)

	
Unfortunately most of the code isn't really documented that good.


nsubsect(MEMBERS (2))

Standard methods:

verb(
	///check that *this satisfies its invariants, abort if not.
	void OK () const

	/// print *this (and substructures) to debugging log
	void print () const

	/**
	protected member. Usually invoked by non-virtual XXXX ()
	*/
	virtual do_XXXX ()

	/**add some data to *this.
	Presence of these methods usually imply that it is not feasible to this
	via  a constructor
	*/
	add (..)

	/// replace some data of *this
	set (..)
)

nsubsect(Constructor)

Every class should have a default constructor.  

Don't use non-default constructors if this can be avoided:

verb(
	Foo f(1)
)

is less readable than

verb(
	Foo f;
	f.x = 1
)

or 

verb(
	Foo f(Foo_convert::int_to_foo (1))
)

nsect(HUNGARIAN NOTATION NAMING CONVENTION)

Proposed is a naming convention derived from the so-called
em(Hungarian Notation).  Macros, code(enum)s and code(const)s are all
uppercase, with the parts of the names separated by underscores.

nsubsect(Types)

description(
dit(code(byte))
    unsigned char. (The postfix _by is ambiguous)
dit(code(b))
    bool
dit(code(bi))
    bit
dit(code(ch))
    char
dit(code(f))
    float
dit(code(i))
    signed integer
dit(code(str))
    string class
dit(code(sz))
    Zero terminated c string
dit(code(u))
    unsigned integer
)

nsubsect(User defined types)

verb(
	/** Slur blah. blah.
	(slur)
	*/
	class Slur {};
	Slur* slur_p = new Slur;
)

nsubsect(Modifiers)

The following types modify the meaning of the prefix. 
These are preceded by the prefixes:

description(
dit(code(a))
    array
dit(code(array))
    user built array.
dit(code(c))
    const. Note that the proper order is code(Type const)
    i.s.o. code(const Type)
dit(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.
dit(code(l))
    temporary pointer to object (link)
dit(code(p))
    pointer to newed object
dit(code(r))
    reference
)

nsubsect(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.

verb(
foo_global_i: a global variable of type int commonly called "foo".
)

static class members do not need the static_ prefix in the name (the
Class::var notation usually makes it clear that it is static)

description(
dit(code(loop_i))
    Variable loop: an integer
dit(code(u))
    Temporary variable: an unsigned integer
dit(code(test_ch))
    Variable test: a character
dit(code(first_name_str))
    Variable first_name: a String class object
dit(code(last_name_ch_a))
    Variable last_name: a code(char) array
dit(code(foo_i_p))
    Variable foo: an code(Int*) that you must delete
dit(code(bar_i_l))
    Variable bar: an code(Int*) that you must not delete
)

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

verb(
	static Array<int*> foo
)

code(foo) can be described as "the static int-pointer user-array", so you get

verb(
	foo_static_l_arr
)



nsect(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.

The following generic identifications are used:

verb(
	up == 1
	left == -1
	right == 1
	down == -1
)

Intervals are pictured lying on a horizontal numberline (Interval[-1]
is the minimum). The 2D plane has +x on the right, +y pointing up.