[Crossfire-wiki] [Crossfire DokuWiki] page added: coding_style_guide

Thu Jun 15 12:06:31 CDT 2006

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Date        : 2006/06/15 17:06

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Edit Summary: import crossfire/doc/Developers/programming_guide

The following is a mirror of //crossfire/doc/Developers/programming_guide/
/ from the server source.

----

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 refle
cts

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 objec
t,

check and make sure the object still exists after insertion - it is possib
le

that the object gets destroyed while being inserted.

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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.

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 requir
ed.

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.

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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/chang
es.

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 l
ost.

7) There is no need to make a seperate diff file for each file

different (ie, treasure.diff, player.diff, etc).  Assuming you follow step
s

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.

Submit all patches to the Sourceforge patch tracker on

http://sourceforge.net/projects/crossfire., and mail an announcement to

crossfire-devel at lists.real-time.com.

IP-Address  : 192.139.27.18

Old Revision: none

New Revision: http://wiki.metalforge.net/doku.php/coding_style_guide

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