[ViewVC] Annotation of: cvs/deliantra/server/doc/programming_guide

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) Identation is either 2 spaces or 4 spaces.  This can be a pain
to read, but most functions should be consistent through the function.

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 the [s/u]int[8/16/32] 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 ANSI C compilers that follow the spec strictly
(gcc does not, even with -strict -ansi)

10) As a followup on 9 above, don't use nonstandard gcc extensions
(// for comment lines, 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.

This 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

Revision:	1.1
Committed:	Fri Feb 3 07:12:30 2006 UTC (18 years, 3 months ago) by root
Branch:	MAIN
Branch point for:	UPSTREAM
Log Message:	Initial revision
#	User	Rev	Content
1	root	1.1	I've redone this file to hopefully make it a little easier to read through
2			and quickly get some idea what to do. There are 3 sections -
3			section 1 is current programming style/hints for developers to make
4			things easier. Section 2 is programming guide for new addition.
5			Section 3 is notes for making patches.
6
7			------------------------------------------------------------------------------
8			Section 1 - currently used conventions/hints for new code writers:
9
10			1) variable abbreviations - op is short for object pointer, ob is for
11			object, and pl is for player.
12
13			2) Some functions are named using the conventions above - the naming reflects
14			what options they take (insert_ob_in_ob takes 2 object structures)
15
16			3) Identation is either 2 spaces or 4 spaces. This can be a pain
17			to read, but most functions should be consistent through the function.
18
19			4) Some structure elements should never be accessed directly - rather,
20			there are other functions to use the values.
21
22			object->owner: This contains the owner id for this object. Use
23			set_owner and get_owner instead. Directly using object->owner
24			is likely to get unpredictable results.
25
26			object->nrof: This contains the number of an object.
27			Since changing this will change the weight of an object, direct
28			access should also be avoided. Use decrease_ob_nr, split_ob,
29			and insert_ob_in_... - the later will merge the objects if
30			applicable.
31
32			5) If using insert_ob_in_map and plan to do further actions with the object,
33			check and make sure the object still exists after insertion - it is possible
34			that the object gets destroyed while being inserted.
35
36			------------------------------------------------------------------------------
37			Section 2 - Style guide for new additions:
38
39			1) Use descriptive variable names. op and pl should only be used for
40			temporary variables (cycling through the list or the like). For variables
41			well defined, use an accurate name (ie, hitter, sack, etc).
42
43			2) Only add name options with #ifdef's to the config file if the behaviour
44			seriously changes the game. Adding a new spell does not warrant an
45			#ifdef. There are already too many options in the config.h file.
46
47			3) Log errors/diagnostics with the LOG function. When doing so,
48			please include the function name - this is especially true for errors.
49
50			4) If you want to add special debug code for certain compiles, generate
51			a unique #define for it - don't use the global DEBUG. For example,
52			NEWCS_DEBUG.
53
54			5) Try to use the [s/u]int[8/16/32] whenever possible. Use the one
55			of appropriate size/type. If not sure, go for the next size up. Do
56			not ever write code assuming that any of those will have an exact number
57			of bits - those types only mean that you will get at least that many
58			bits - you may get more.
59
60			6) The exception to #5 above is strings. Continue to use 'char', since
61			the signedness of functions that take string options can differ system
62			to system, and generate excessive warnings if the wrong sign is used.
63
64			7) When adding new function, include a comment of what the function is
65			supposed to do, what options it takes, and what if any value it returns.
66			This makes debugging of such functions easier, and also makes it better
67			known to other developers if that function might be useful to them.
68
69			8) Try to keep lines to less than 80 columns when possible. This is not
70			a strict requirement - don't break up some complex comparison because the
71			line would otherwise be 83 characters long. Xterms can be resized to most
72			any width. However, use your judgement on whether breaking up a long
73			line would make something more or less readable.
74
75			9) Assume all names use one namespace. For example, if there is a
76			struct called spell, don't make the name of an optional parameter spell.
77			This will break on ANSI C compilers that follow the spec strictly
78			(gcc does not, even with -strict -ansi)
79
80			10) As a followup on 9 above, don't use nonstandard gcc extensions
81			(// for comment lines, ability to nest functions, declare arrays with
82			variable bounds, etc.) Likewise, don't use special system functions - don't
83			assume the target system will be bsd or svr4 - if using a potentially non
84			standard function, add checks in the autoconf script and include a version
85			of the function in case it is not on that system. They key word here is
86			portability - don't assume everyone else has the same system as you do.
87
88			11) Write code that can easily be maintained in the future, not code that
89			is easiest to write at that second. This basically means don't do the
90			quick and ugly hack, but instead fix it properly.
91
92			12) Use 4 space indentation. While a lot of old code may have 2 space,
93			the move to 4 space will make future readability easier.
94
95			Take from http://www.jwz.org/doc/tabs-vs-spaces.html
96
97			In Emacs, to set the mod-N indentation used when you hit the TAB key, do this:
98
99			(setq c-basic-indent 2)
100			or (setq c-basic-indent 4)
101
102			To cause the TAB file-character to be interpreted as mod-N indentation, do this:
103
104			(setq tab-width 4)
105			or (setq tab-width 8)
106
107			To cause TAB characters to not be used in the file for compression, and for only
108			spaces to be used, do this:
109
110			(setq indent-tabs-mode nil)
111
112			To keep myself honest (that is, to ensure that no tabs ever end up in source
113			files that I am editing) I also do this in my .emacs file:
114
115			(defun java-mode-untabify ()
116			(save-excursion
117			(goto-char (point-min))
118			(while (re-search-forward "[ \t]+$" nil t)
119			(delete-region (match-beginning 0) (match-end 0)))
120			(goto-char (point-min))
121			(if (search-forward "\t" nil t)
122			(untabify (1- (point)) (point-max))))
123			nil)
124
125			(add-hook 'java-mode-hook
126			'(lambda ()
127			(make-local-variable 'write-contents-hooks)
128			(add-hook 'write-contents-hooks 'java-mode-untabify)))
129
130			That ensures that, even if I happened to insert a literal tab in the file by
131			hand (or if someone else did when editing this file earlier), those tabs get
132			expanded to spaces when I save. This assumes that you never use tabs in places
133			where they are actually significant, like in string or character constants, but
134			I never do that: when it matters that it is a tab, I always use '\t' instead.
135
136			To get vim to interpret tab as an ``indent'' command instead of an insert-a-tab
137			command, do this:
138
139			set softtabstop=2
140
141			To set the mod-N indentation used when you hit the tab key in vim (what Emacs
142			calls c-basic-indent), do this:
143
144			set shiftwidth=2
145
146			To cause the TAB file-character to be displayed as mod-N in vi and vim (what
147			Emacs calls tab-width), do this:
148
149			set tabstop=4
150
151			To cause TAB characters to not be used in the file for compression, and for only
152			spaces to be used (what emacs calls indent-tabs-mode), do this:
153
154			set expandtab
155
156			12.1) I work on several projects and each uses a different indent format. What
157			do I do?
158
159			Taken from an email from Eric Estabrooks <estabroo@talkware.net>, which is
160			based on info found in the linux kernel.
161
162			add to your .emacs
163			; linux kernel c mode
164			(defun linux-c-mode ()
165			"C mode with adjusted defaults for use with the Linux kernel."
166			(interactive)
167			(c-mode)
168			(c-set-style "K&R")
169			(setq c-basic-offset 8))
170
171			; set linux kernel mode for anything in /usr/src/linux*
172			(setq auto-mode-alist (cons '("/usr/src/linux./.\\.[ch]$" . linux-c-mode)
173			auto-mode-alist))
174
175			13)
176			/*
177			* do block
178			* comment like
179			* this
180			*/
181
182			/*
183			and not
184			like this
185			*/
186
187			/* if you are doing a single line comment, this method is fine */
188
189			Its much easier to spot the block comments if they all start with *,
190			and these comments tend to be worth noticing.
191
192			14) As discussed on irc, the preferred style for expressions is like this:
193
194			if (expression) {
195			statement;
196			statement;
197			}
198
199			if <space> (expression), the space between the if and expression is required.
200
201			NOT like this:
202
203			if (expression)
204			{
205			statement;
206			statement;
207			}
208
209			15) The preferred style of formal parameters:
210
211			void myFooFunction(param1, param2, param3) {
212			statement;
213			statement;
214			}
215
216			No space after the left paren, no space before the right paren.
217			Comma right after the formal param, space right after the comma.
218
219
220			16) Local variable names. Just a rules of thumb.
221
222			This are ok:
223
224			int mylongvarname;
225			int my_long_var_name;
226
227			Please do NOT use caps expect for typedefs, enums and defines.
228
229			------------------------------------------------------------------------------
230			Section 3 - sending in patches:
231
232			1) Please send patches on a bug fix or feature enhancement basis
233			individually, and not make mega patches. A diff that changes 10
234			things is first more difficult for me to look over and understand as
235			unrelated changes might be going on. It is also harder for me to reject
236			part of a patch (feature X is nice, but Y doesn't work).
237
238			2) Please state in the message included with the patch what it fixes/changes.
239			Too often, I get patches which is just a bunch of source code, and I have
240			no idea if I want to incorporate it, or even if the bug is still there.
241			Please also state what version of crossfire the diff is for.
242
243			3) I will assume any patches mailed directly to me are to be included.
244			If posting a patch on the mailing list (either source or ftp location),
245			please explicity state whether or not you want that patch incorporated
246			into the master source. Many times, a patch may be made available on
247			an expiremental basis which is not ready for widespread distribution.
248
249			4) When making patches, please make context diffs. Please also include
250			the directory that the file is in (run the diff in the top level
251			directory). Please make 5 line context diffs - large line context diffs
252			are fine if you think that may make it easier.
253
254			Example:
255
256			'diff -c5 (oldfile) (newfile)'
257
258			You can also do diffs of entire directories. Do do this, type:
259
260			'diff -c5 -r (old_directory) (new_directory)'
261
262			An example:
263
264			'diff -c5 -r crossfire-0.90.1 crossfire-0.90.2'
265
266			5) Gnu diff will include files that did not exist before. Other diff
267			programs may not do this.
268
269			6) If your diff looks excessively long and you made a lot of formatting
270			changes, you can add -w to the diff options to have it ignore whitespace.
271			Note that this will then mean that those formatting changes will then be lost.
272
273			7) There is no need to make a seperate diff file for each file
274			different (ie, treasure.diff, player.diff, etc). Assuming you follow steps
275			1-6, all the diffs can be contained in one file, and patch will deal with
276			it just fine.
277
278			8) If you need to send a map, new archetypes, or other new files where
279			a diff doesn't make since, a uuencoded tar file will work just fine.
280
281			Mail all patches to crossfire-devel@lists.real-time.com
282