Here is the order in which code should be laid out in a file:
+ - commented program name and one-line description
- commented author name and email address(es)
- commented GPL boilerplate
- - commented description of program
+ - commented longer description / notes for the program (if needed)
- #includes and #defines
- - const and globals variables
+ - const and global variables
- function declarations (if necessary)
- function implementations
up front.
-Tabs vs Spaces in Line Indentation
+Tabs vs. Spaces in Line Indentation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The preference in Busybox is to indent lines with tabs. Do not indent lines
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
+lines is that you can set your editor to display tabs at *whatever* number of
spaces is desired and the code will still look fine.
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:
+ single term (even if it is a compound term) such as:
if (str[idx] == '/' && str[idx-1] != '\\')
~~~~~~~~~~~~~~~
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
+next line with no spacing before it. However, if a bracket 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:
+between it and the opening control block statement. Examples:
Don't do this:
+ while (!done)
+ {
+
+ do
+ {
+
+ Don't do this either:
+
while (!done){
do{
while (foo) {
for (i = 0; i < n; i++) {
- Do functions like this:
+ But do functions like this:
static int my_func(int foo, char bar)
...
Cuddled Elses
~~~~~~~~~~~~~
-Also, please "cuddle" your else statments by putting the else keyword on the
-same line after the right bracket that closes an 'if' statment.
+Also, please "cuddle" your else statements by putting the else keyword on the
+same line after the right bracket that closes an 'if' statement.
Don't do this:
stmt;
}
+The exception to this rule is if you want to include a comment before the else
+block. Example:
+
+ if (foo) {
+ stmts...
+ }
+ /* otherwise, we're just kidding ourselves, so re-frob the input */
+ else {
+ other_stmts...
+ }
+
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
+used to separate 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,
+variety of sources. This explains why the current codebase contains such a
+hodge-podge 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.
+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 exercise to the reader for
+now.
Tip and Pointers
The following are simple coding guidelines that should be followed:
- - When in doubt about the propper behavior of a busybox program (output,
+ - When in doubt about the proper behavior of a Busybox program (output,
formatting, options, etc.), model it after the equivalent GNU program.
Doesn't matter how that program behaves on some other flavor of *NIX;
doesn't matter what the POSIX standard says or doesn't say, just model
- busybox programs after their GNU counterparts and nobody has to get hurt.
+ Busybox programs after their GNU counterparts and nobody has to get hurt.
- 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
+ instead. This makes the compiler do type checking 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.
+ programs much easier since the value of the variable can be easily
+ displayed.
- 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
+ the global name space 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).
+ - Put all help/usage messages in usage.c. Put other strings in messages.c.
+ Putting these strings into their own file is a calculated decision designed
+ to confine spelling errors to a single place and aid internationalization
+ efforts, if needed. (Side Note: we might want to use a single file instead
+ of two, food for thought).
- There's a right way and a wrong way to test for sting equivalence with
strcmp:
The use of the "equals" (==) operator in the latter example makes it much
more obvious that you are testing for equivalence. The former example with
- the "not" (!) operator makes it look like you are testing for an error.
+ the "not" (!) operator makes it look like you are testing for an error. In
+ a more perfect world, we would have a streq() function in the string
+ library, but that ain't the world we're living in.
- Do not use old-style function declarations that declare variable types
between the parameter list and opening bracket. Example:
projects / platform / upstream / busybox.git / commitdiff