style-guide.txt

I've redone this file to hopefully make it a little easier to read through
and quickly get some idea what to do.  There are 3 sections -
section 1 is current programming style/hints for developers to make
things easier.  Section 2 is programming guide for new addition.
Section 3 is notes for making patches.

------------------------------------------------------------------------------
Section 1 - currently used conventions/hints for new code writers:

1) variable abbreviations - op is short for object pointer, ob is for
object, and pl is for player.

2) Some functions are named using the conventions above - the naming reflects
what options they take (insert_ob_in_ob takes 2 object structures)

3) Indentation is 4 spaces.

4) Some structure elements should never be accessed directly - rather,
there are other functions to use the values.

     	object->owner:  This contains the owner id for this object.  Use
	set_owner and get_owner instead.  Directly using object->owner
	is likely to get unpredictable results.

	object->nrof:  This contains the number of an object.
	Since changing this will change the weight of an object, direct
	access should also be avoided.  Use decrease_ob_nr, split_ob,
	and insert_ob_in_... - the later will merge the objects if
	applicable.

5) If using insert_ob_in_map and plan to do further actions with the object,
check and make sure the object still exists after insertion - it is possible
that the object gets destroyed while being inserted.

------------------------------------------------------------------------------
Section 2 - Style guide for new additions:

1) Use descriptive variable names.  op and pl should only be used for
temporary variables (cycling through the list or the like).  For variables
well defined, use an accurate name (ie, hitter, sack, etc).

2) Only add name options with #ifdef's to the config file if the behaviour
seriously changes the game.  Adding a new spell does not warrant an
#ifdef.  There are already too many options in the config.h file.

3) Log errors/diagnostics with the LOG function.  When doing so,
please include the function name - this is especially true for errors.

4) If you want to add special debug code for certain compiles, generate
a unique #define for it - don't use the global DEBUG.  For example,
NEWCS_DEBUG.

5) Try to use C99 types whenever possible.  Use the one
of appropriate size/type.  If not sure, go for the next size up.  Do
not ever write code assuming that any of those will have an exact number
of bits - those types only mean that you will get at least that many
bits - you may get more.

6) The exception to #5 above is strings.  Continue to use 'char', since
the signedness of functions that take string options can differ system
to system, and generate excessive warnings if the wrong sign is used.

7) When adding new function, include a comment of what the function is
supposed to do, what options it takes, and what if any value it returns.
This makes debugging of such functions easier, and also makes it better
known to other developers if that function might be useful to them.

8) Try to keep lines to less than 80 columns when possible.  This is not
a strict requirement - don't break up some complex comparison because the
line would otherwise be 83 characters long.  Xterms can be resized to most
any width.  However, use your judgement on whether breaking up a long
line would make something more or less readable.

9) Assume all names use one namespace.  For example, if there is a
struct called spell, don't make the name of an optional parameter spell.
This will break on C compilers that follow the spec strictly

10) As a followup on 9 above, don't use nonstandard gcc extensions
(ability to nest functions, declare arrays with variable bounds, etc.)
Likewise, don't use special system functions - don't
assume the target system will be bsd or svr4 - if using a potentially non
standard function, add checks in the autoconf script and include a version
of the function in case it is not on that system.  They key word here is
portability - don't assume everyone else has the same system as you do.

11) Write code that can easily be maintained in the future, not code that
is easiest to write at that second.  This basically means don't do the
quick and ugly hack, but instead fix it properly.

12) Use 4 space indentation.  While a lot of old code may have 2 space,
the move to 4 space will make future readability easier.

Take from http://www.jwz.org/doc/tabs-vs-spaces.html

In Emacs, to set the mod-N indentation used when you hit the TAB key, do this:

      (setq c-basic-indent 2)
      or (setq c-basic-indent 4)

To cause the TAB file-character to be interpreted as mod-N indentation, do this:

      (setq tab-width 4)
      or (setq tab-width 8)

To cause TAB characters to not be used in the file for compression, and for only
spaces to be used, do this:

(setq indent-tabs-mode nil)

To keep myself honest (that is, to ensure that no tabs ever end up in source
files that I am editing) I also do this in my .emacs file:

(defun java-mode-untabify ()
    (save-excursion
      (goto-char (point-min))
      (while (re-search-forward "[ \t]+$" nil t)
        (delete-region (match-beginning 0) (match-end 0)))
      (goto-char (point-min))
      (if (search-forward "\t" nil t)
          (untabify (1- (point)) (point-max))))
    nil)

  (add-hook 'java-mode-hook
            '(lambda ()
               (make-local-variable 'write-contents-hooks)
               (add-hook 'write-contents-hooks 'java-mode-untabify)))

That ensures that, even if I happened to insert a literal tab in the file by
hand (or if someone else did when editing this file earlier), those tabs get
expanded to spaces when I save. This assumes that you never use tabs in places
where they are actually significant, like in string or character constants, but
I never do that: when it matters that it is a tab, I always use '\t' instead.

To get vim to interpret tab as an ``indent'' command instead of an insert-a-tab
command, do this:

set softtabstop=2

To set the mod-N indentation used when you hit the tab key in vim (what Emacs
calls c-basic-indent), do this:

set shiftwidth=2

To cause the TAB file-character to be displayed as mod-N in vi and vim (what
Emacs calls tab-width), do this:

set tabstop=4

To cause TAB characters to not be used in the file for compression, and for only
spaces to be used (what emacs calls indent-tabs-mode), do this:

set expandtab

12.1) I work on several projects and each uses a different indent format. What
      do I do?

Taken from an email from Eric Estabrooks <estabroo@talkware.net>, which is
based on info found in the linux kernel.

add to your .emacs
; linux kernel c mode
(defun linux-c-mode ()
   "C mode with adjusted defaults for use with the Linux kernel."
   (interactive)
   (c-mode)
   (c-set-style "K&R")
   (setq c-basic-offset 8))

; set linux kernel mode for anything in /usr/src/linux*
(setq auto-mode-alist (cons '("/usr/src/linux.*/.*\\.[ch]$" . linux-c-mode)
                        auto-mode-alist))

13)
 /*
  * do block
  * comment like
  * this
  */

  /*
    and not
    like this
   */

  /* if you are doing a single line comment, this method is fine */

  Its much easier to spot the block comments if they all start with *,
  and these comments tend to be worth noticing.

14) As discussed on irc, the preferred style for expressions is like this:

if (expression) {
    statement;
    statement;
}

if <space> (expression), the space between the if and expression is required.

NOT like this:

if (expression)
{
    statement;
    statement;
}

15) The preferred style of formal parameters:

void myFooFunction(param1, param2, param3) {
    statement;
    statement;
}

No space after the left paren, no space before the right paren.
Comma right after the formal param, space right after the comma.


16) Local variable names. Just a rules of thumb.

These are ok:

  int mylongvarname;
  int my_long_var_name;

Please do NOT use caps expect for typedefs, enums and defines.

------------------------------------------------------------------------------
Section 3 - sending in patches:

1) Please send patches on a bug fix or feature enhancement basis
individually, and not make mega patches.  A diff that changes 10
things is first more difficult for me to look over and understand as
unrelated changes might be going on.  It is also harder for me to reject
part of a patch (feature X is nice, but Y doesn't work).

2) Please state in the message included with the patch what it fixes/changes.
Too often, I get patches which is just a bunch of source code, and I have
no idea if I want to incorporate it, or even if the bug is still there.
Please also state what version of crossfire the diff is for.

3) I will assume any patches mailed directly to me are to be included.
If posting a patch on the mailing list (either source or ftp location),
please explicity state whether or not you want that patch incorporated
into the master source.  Many times, a patch may be made available on
an expiremental basis which is not ready for widespread distribution.

4) When making patches, please make context diffs.  Please also include
the directory that the file is in (run the diff in the top level
directory).  Please make 5 line context diffs - large line context diffs
are fine if you think that may make it easier.

 Example:

	   'diff -c5 (oldfile) (newfile)'

	You can also do diffs of entire directories.  Do do this, type:

	    'diff -c5 -r (old_directory) (new_directory)'

	An example:

	    'diff -c5 -r crossfire-0.90.1 crossfire-0.90.2'

5) Gnu diff will include files that did not exist before.  Other diff
programs may not do this.

6) If your diff looks excessively long and you made a lot of formatting
changes, you can add -w to the diff options to have it ignore whitespace.
Note that this will then mean that those formatting changes will then be lost.

7) There is no need to make a seperate diff file for each file
different (ie, treasure.diff, player.diff, etc).  Assuming you follow steps
1-6, all the diffs can be contained in one file, and patch will deal with
it just fine.

8) If you need to send a map, new archetypes, or other new files where
a diff doesn't make since, a uuencoded tar file will work just fine.

Mail all patches to crossfire-devel@lists.real-time.com