First revision of the Busybox Style Guide and an accompanying .indent.pro

file.
author: Mark Whitley <markw@lineo.com> 2000-07-24 22:36:06 +0000
committer: Mark Whitley <markw@lineo.com> 2000-07-24 22:36:06 +0000
commit: 40bfc763855145694f43f5eee5088a2361da56ed (patch)
tree: 612d386772ff00e80cadeb75812e4cd1b1904aaa /docs/style-guide.txt
parent: e99f7500e0475bcef25f3125efdf847c7382c58f (diff)
download: busybox-w32-40bfc763855145694f43f5eee5088a2361da56ed.tar.gz
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diff --git a/docs/style-guide.txt b/docs/style-guide.txt
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+Busybox Style Guide
+===================
+This document describes the coding style conventions used in Busybox. If you
+add a new file to Busybox or are editing an existing file, please format your
+code according to this style. If you are the maintainer of a file that does
+not follow these guidelines, please -- at your own convenience -- modify the
+file(s) you maintain to bring them into conformance with this style guide.
+Please note that this is a low priority task.
+To help you format the whitespace of your programs, an ".indent.pro" file is
+included in the main Busybox source directory that contains option flags to
+format code as per this style guide. This way you can run GNU indent on your
+files by typing 'indent myfile.c myfile.h' and it will magically apply all the
+right formatting rules to your file. Please _do_not_ run this on all the files
+in the directory, just your own.
+Declaration Order
+-----------------
+Here is the order in which code should be laid out in a file:
+ - commented author name and email address(es)
+ - commented GPL boilerplate
+ - commented description of program
+ - #includes and #defines
+ - const and globals variables
+ - function declarations (if necessary)
+ - function implementations
+Whitespace
+----------
+Tabs vs Spaces in Line Indentation: The preference in Busybox is to indent
+lines with tabs. Do not indent lines with spaces and do not indents lines
+using a mixture of tabs and spaces. (The indentation style in the Apache and
+Postfix source does this sort of thing: \s\s\s\sif (expr) {\n\tstmt; --ick.)
+The only exception to this rule is multi-line comments that use an asterisk at
+the beginning of each line, i.e.:
+        /t/*
+        /t * This is a block comment.
+        /t * Note that it has multiple lines
+        /t * and that the beginning of each line has a tab plus a space
+        /t * except for the opening '/*' line where the slash
+        /t * is used instead of a space.
+        /t */
+Furthermore, The preference is that tabs be set to display at four spaces
+wide, but the beauty of using only tabs (and not spaces) at the beginning of
+lines is that you can set your editor to display tabs at *watever* number of
+spaces is desired and the code will still look fine.
+Operator Spacing: Put spaces between terms and operators. Example:
+        Don't do this:
+                for(i=0;i<num_items;i++){
+        Do this instead:
+                for (i = 0; i < num_items; i++) {
+        While it extends the line a bit longer, the spaced version is more
+        readable. An allowable exception to this rule is the situation where
+        excluding the spacing makes it more obvious that we are dealing with a
+        single term (even if it is a compund term) such as:
+                if (str[idx] == '/' && str[idx-1] != '\\')
+        or
+                if ((argc-1) - (optind+1) > 0)
+Bracket Spacing: If an opening bracket starts a function, it should be on the
+next line with no spacing before it. However, if a bracet follows an opening
+control block, it should be on the same line with a single space (not a tab)
+between it and the opening control block statment. Examples:
+        Don't do this:
+                while (!done){
+                do{
+        Do this instead:
+                while (!done) {
+                do {
+Also, please "cuddle" your else statments by putting the else keyword on the
+same line after the right bracket that closes an 'if' statment.
+        Don't do this:
+        if (foo) {
+                stmt;
+        }
+        else {
+                stmt;
+        }
+        Do this instead:
+        if (foo) {
+                stmt;
+        } else {
+                stmt;
+        }
+Paren Spacing: Put a space between C keywords and left parens, but not between
+function names and the left paren that starts it's parameter list (whether it
+is being declared or called). Examples:
+        Don't do this:
+                while(foo) {
+                for(i = 0; i < n; i++) {
+        Do this instead:
+                while (foo) {
+                for (i = 0; i < n; i++) {
+        Do functions like this:
+                static int my_func(int foo, char bar)
+                ...
+                baz = my_func(1, 2);
+Variable and Function Names
+---------------------------
+Use the K&R style with names in all lower-case and underscores occasionally
+used to seperate words (e.g. "variable_name" and "numchars" are both
+acceptable). Using underscores makes variable and function names more readable
+because it looks like whitespace; using lower-case is easy on the eyes.
+Note: The Busybox codebase is very much a mixture of code gathered from a
+variety of locations. This explains why the current codebase contains such a
+plethora of different naming styles (Java, Pascal, K&R, just-plain-weird,
+etc.). The K&R guideline explained above should therefore be used on new files
+that are added to the repository. Furthermore, the maintainer of an existing
+file that uses alternate naming conventions should -- at his own convenience
+-- convert those names over to K&R style; converting variable names is a very
+low priority task. Perhaps in the future we will include some magical Perl
+script that can go through and convert files--left as an exersize to the
+reader.
+Tip and Pointers
+----------------
+The following are simple coding guidelines that should be followed:
+ - Don't use a '#define var 80' when you can use 'static const int var 80'
+   instead. This makes the compiler do typechecking for you (rather than
+   relying on the more error-prone preprocessor) and it makes debugging
+   programs much easier since the value of the variable can be easily queried.
+ - If a const variable is used in only one function, do not make it global to
+   the file. Instead, declare it inside the function body.
+ - Inside applet files, all functions should be declared static so as to keep
+   the global namespace clean. The only exception to this rule is the
+   "applet_main" function which must be declared extern.
+ - If you write a function that performs a task that could be useful outside
+   the immediate file, turn it into a general-purpose function with no ties to
+   any applet and put it in the utility.c file instead.
+ - Put all help/usage messages in usage.c. Put other strings in messages.c
+   (Side Note: we might want to use a single file instead of two, food for
+   thought).
+ - Do not use old-style function declarations that declare variable types
+   between the parameter list and opening bracket. Example:
+        Don't do this:
+                int foo(parm1, parm2)
+                        char parm1;
+                        float parm2;
+                {
+                        ....
+        Do this instead:
+                int foo(char parm1, float parm2)
+                {
+                        ....
+ - Please use brackets on all if and else statements, even if it is only one
+   line. Example:
+        Don't do this:
+                if (foo)
+                        stmt;
+                else
+                        stmt;
+        Do this instead:
+                if (foo) {
+                        stmt;
+                } else {
+                        stmt;
+                }
+        The "bracketless" approach is error prone because someday you might add a
+        line like this:
+                if (foo)
+                        stmt;
+                        new_line();
+                else
+                        stmt;
+        And the resulting behavior of your program would totally bewilder you.
+        (Don't laugh, it happens to us all.) Remember folks, this is C, not
+        Python.
author	Mark Whitley <markw@lineo.com>	2000-07-24 22:36:06 +0000
committer	Mark Whitley <markw@lineo.com>	2000-07-24 22:36:06 +0000
commit	40bfc763855145694f43f5eee5088a2361da56ed (patch)
tree	612d386772ff00e80cadeb75812e4cd1b1904aaa /docs/style-guide.txt
parent	e99f7500e0475bcef25f3125efdf847c7382c58f (diff)
download	busybox-w32-40bfc763855145694f43f5eee5088a2361da56ed.tar.gz busybox-w32-40bfc763855145694f43f5eee5088a2361da56ed.tar.bz2 busybox-w32-40bfc763855145694f43f5eee5088a2361da56ed.zip

diff --git a/docs/style-guide.txt b/docs/style-guide.txt new file mode 100644 index 000000000..28fb1fbfc --- /dev/null +++ b/docs/style-guide.txt
@@ -0,0 +1,224 @@
	1	Busybox Style Guide
	2	===================
	3
	4	This document describes the coding style conventions used in Busybox. If you
	5	add a new file to Busybox or are editing an existing file, please format your
	6	code according to this style. If you are the maintainer of a file that does
	7	not follow these guidelines, please -- at your own convenience -- modify the
	8	file(s) you maintain to bring them into conformance with this style guide.
	9	Please note that this is a low priority task.
	10
	11	To help you format the whitespace of your programs, an ".indent.pro" file is
	12	included in the main Busybox source directory that contains option flags to
	13	format code as per this style guide. This way you can run GNU indent on your
	14	files by typing 'indent myfile.c myfile.h' and it will magically apply all the
	15	right formatting rules to your file. Please _do_not_ run this on all the files
	16	in the directory, just your own.
	17
	18	Declaration Order
	19	-----------------
	20
	21	Here is the order in which code should be laid out in a file:
	22
	23	- commented author name and email address(es)
	24	- commented GPL boilerplate
	25	- commented description of program
	26	- #includes and #defines
	27	- const and globals variables
	28	- function declarations (if necessary)
	29	- function implementations
	30
	31	Whitespace
	32	----------
	33
	34	Tabs vs Spaces in Line Indentation: The preference in Busybox is to indent
	35	lines with tabs. Do not indent lines with spaces and do not indents lines
	36	using a mixture of tabs and spaces. (The indentation style in the Apache and
	37	Postfix source does this sort of thing: \s\s\s\sif (expr) {\n\tstmt; --ick.)
	38	The only exception to this rule is multi-line comments that use an asterisk at
	39	the beginning of each line, i.e.:
	40
	41	/t/*
	42	/t * This is a block comment.
	43	/t * Note that it has multiple lines
	44	/t * and that the beginning of each line has a tab plus a space
	45	/t * except for the opening '/*' line where the slash
	46	/t * is used instead of a space.
	47	/t */
	48
	49	Furthermore, The preference is that tabs be set to display at four spaces
	50	wide, but the beauty of using only tabs (and not spaces) at the beginning of
	51	lines is that you can set your editor to display tabs at watever number of
	52	spaces is desired and the code will still look fine.
	53
	54
	55	Operator Spacing: Put spaces between terms and operators. Example:
	56
	57	Don't do this:
	58
	59	for(i=0;i<num_items;i++){
	60
	61	Do this instead:
	62
	63	for (i = 0; i < num_items; i++) {
	64
	65	While it extends the line a bit longer, the spaced version is more
	66	readable. An allowable exception to this rule is the situation where
	67	excluding the spacing makes it more obvious that we are dealing with a
	68	single term (even if it is a compund term) such as:
	69
	70	if (str[idx] == '/' && str[idx-1] != '\\')
	71
	72	or
	73
	74	if ((argc-1) - (optind+1) > 0)
	75
	76
	77	Bracket Spacing: If an opening bracket starts a function, it should be on the
	78	next line with no spacing before it. However, if a bracet follows an opening
	79	control block, it should be on the same line with a single space (not a tab)
	80	between it and the opening control block statment. Examples:
	81
	82	Don't do this:
	83
	84	while (!done){
	85	do{
	86
	87	Do this instead:
	88
	89	while (!done) {
	90	do {
	91
	92	Also, please "cuddle" your else statments by putting the else keyword on the
	93	same line after the right bracket that closes an 'if' statment.
	94
	95	Don't do this:
	96
	97	if (foo) {
	98	stmt;
	99	}
	100	else {
	101	stmt;
	102	}
	103
	104	Do this instead:
	105
	106	if (foo) {
	107	stmt;
	108	} else {
	109	stmt;
	110	}
	111
	112
	113	Paren Spacing: Put a space between C keywords and left parens, but not between
	114	function names and the left paren that starts it's parameter list (whether it
	115	is being declared or called). Examples:
	116
	117	Don't do this:
	118
	119	while(foo) {
	120	for(i = 0; i < n; i++) {
	121
	122	Do this instead:
	123
	124	while (foo) {
	125	for (i = 0; i < n; i++) {
	126
	127	Do functions like this:
	128
	129	static int my_func(int foo, char bar)
	130	...
	131	baz = my_func(1, 2);
	132
	133	Variable and Function Names
	134	---------------------------
	135
	136	Use the K&R style with names in all lower-case and underscores occasionally
	137	used to seperate words (e.g. "variable_name" and "numchars" are both
	138	acceptable). Using underscores makes variable and function names more readable
	139	because it looks like whitespace; using lower-case is easy on the eyes.
	140
	141	Note: The Busybox codebase is very much a mixture of code gathered from a
	142	variety of locations. This explains why the current codebase contains such a
	143	plethora of different naming styles (Java, Pascal, K&R, just-plain-weird,
	144	etc.). The K&R guideline explained above should therefore be used on new files
	145	that are added to the repository. Furthermore, the maintainer of an existing
	146	file that uses alternate naming conventions should -- at his own convenience
	147	-- convert those names over to K&R style; converting variable names is a very
	148	low priority task. Perhaps in the future we will include some magical Perl
	149	script that can go through and convert files--left as an exersize to the
	150	reader.
	151
	152
	153	Tip and Pointers
	154	----------------
	155
	156	The following are simple coding guidelines that should be followed:
	157
	158	- Don't use a '#define var 80' when you can use 'static const int var 80'
	159	instead. This makes the compiler do typechecking for you (rather than
	160	relying on the more error-prone preprocessor) and it makes debugging
	161	programs much easier since the value of the variable can be easily queried.
	162
	163	- If a const variable is used in only one function, do not make it global to
	164	the file. Instead, declare it inside the function body.
	165
	166	- Inside applet files, all functions should be declared static so as to keep
	167	the global namespace clean. The only exception to this rule is the
	168	"applet_main" function which must be declared extern.
	169
	170	- If you write a function that performs a task that could be useful outside
	171	the immediate file, turn it into a general-purpose function with no ties to
	172	any applet and put it in the utility.c file instead.
	173
	174	- Put all help/usage messages in usage.c. Put other strings in messages.c
	175	(Side Note: we might want to use a single file instead of two, food for
	176	thought).
	177
	178	- Do not use old-style function declarations that declare variable types
	179	between the parameter list and opening bracket. Example:
	180
	181	Don't do this:
	182
	183	int foo(parm1, parm2)
	184	char parm1;
	185	float parm2;
	186	{
	187	....
	188
	189	Do this instead:
	190
	191	int foo(char parm1, float parm2)
	192	{
	193	....
	194
	195	- Please use brackets on all if and else statements, even if it is only one
	196	line. Example:
	197
	198	Don't do this:
	199
	200	if (foo)
	201	stmt;
	202	else
	203	stmt;
	204
	205	Do this instead:
	206
	207	if (foo) {
	208	stmt;
	209	} else {
	210	stmt;
	211	}
	212
	213	The "bracketless" approach is error prone because someday you might add a
	214	line like this:
	215
	216	if (foo)
	217	stmt;
	218	new_line();
	219	else
	220	stmt;
	221
	222	And the resulting behavior of your program would totally bewilder you.
	223	(Don't laugh, it happens to us all.) Remember folks, this is C, not
	224	Python.