			       Vim coding style

These are the rules to use when making changes to the Vim source code.  Please
stick to these rules, to keep the sources readable and maintainable.

This list is not complete.  Look in the source code for more examples.


MAKING CHANGES

The basic steps to make changes to the code:
1. Adjust the documentation.  Doing this first gives you an impression of how
   your changes affect the user.
2. Make the source code changes.
3. Check ../doc/todo.txt if the change affects any listed item.
4. Make a patch with "diff -c" against the unmodified code and docs.
5. Make a note about what changed and include it with the patch.


USE OF COMMON FUNCTIONS

Some functions that are common to use, have a special Vim version.  Always
consider using the Vim version, because they were introduced with a reason.

NORMAL NAME	VIM NAME	DIFFERENCE OF VIM VERSION
free()		vim_free()	Checks for freeing NULL
malloc()	alloc()		Checks for out of memory situation
malloc()	lalloc()	Like alloc(), but has long argument
strcpy()	STRCPY()	Includes cast to (char *), for char_u * args
strchr()	vim_strchr()	Accepts special characters
strrchr()	vim_strrchr()	Accepts special characters
isspace()	vim_isspace()	Can handle characters > 128
iswhite()	vim_iswhite()	Only TRUE for Tab and space
memcpy()	vim_memmove()	Handles overlapped copies
bcopy()		vim_memmove()	Handles overlapped copies
memset()	vim_memset()	Uniform for all systems


NAMES

Because of the requirement that Vim runs on as many systems as possible, we
need to avoid using names that are already defined by the system.  This is a
list of names that are known to cause trouble.  The name is given as a regexp
pattern.

is.*()		POSIX, ctype.h
to.*()		POSIX, ctype.h

d_.*		POSIX, dirent.h
l_.*		POSIX, fcntl.h
gr_.*		POSIX, grp.h
pw_.*		POSIX, pwd.h
sa_.*		POSIX, signal.h
mem.*		POSIX, string.h
str.*		POSIX, string.h
wcs.*		POSIX, string.h
st_.*		POSIX, stat.h
tms_.*		POSIX, times.h
tm_.*		POSIX, time.h
c_.*		POSIX, termios.h
MAX.*		POSIX, limits.h
__.*		POSIX, system
_[A-Z].*	POSIX, system
E[A-Z0-9]*	POSIX, errno.h

wait		don't use as argument to a function, conflicts with types.h
index		shadows global declaration
time		shadows global declaration
new		C++ reserved keyword
try		Borland C++ doesn't like it to be used as a variable.

basename()	GNU string function
dirname()	GNU string function
get_env_value()	Linux system function


VARIOUS

Don't use '\"', some compilers can't handle it.  '"' works fine.

Don't use:
    #if HAVE_SOME
Some compilers can't handle that and complain that "HAVE_SOME" is not defined.
Use
    #ifdef HAVE_SOME
or
    #if defined(HAVE_SOME)


STYLE

General rule: One statement per line.

Wrong:	    if (cond) a = 1;

OK:	    if (cond)
		a = 1;

Wrong:	    while (cond);

OK:	    while (cond)
		;

Wrong:	    do a = 1; while (cond);

OK:	    do
		a = 1;
	    while (cond);


Functions start with:

Wrong:	int function_name(int arg1, int arg2)

OK:	/*
	 * Explanation of what this function is used for.
	 *
	 * Return value explanation.
	 */
	    int
	function_name(arg1, arg2)
	    int	    	arg1;		/* short comment about arg1 */
	    int	    	arg2;		/* short comment about arg2 */
	{
	    int		local;		/* comment about local */

	    local = arg1 * arg2;

NOTE: Don't use ANSI style function declarations.  Some people still have to
use compilers that don't support it.


SPACES AND PUNCTUATION

No space between a function name and the bracket:

Wrong:  func (arg);
OK:	func(arg);

Do use a space after if, while, switch, etc.

Wrong:	if(arg)		for(;;)
OK	if (arg)	for (;;)

Use a space after a comma and semicolon:

Wrong:  func(arg1,arg2);	for (i = 0;i < 2;++i)
OK:	func(arg1, arg2);	for (i = 0; i < 2; ++i)

Use a space before and after '=', '+', '/', etc.

Wrong:	var=a*5;
OK:	var = a * 5;

In general: Use empty lines to group lines of code together.  This makes it
more easy to quickly see what is being done.
