STYLE

@@ -1,26 +1,33 @@
+“Everyone knows that debugging is twice as hard as writing a program in the
+first place. So if you’re as clever as you can be when you write it, how
+will you ever debug it?”
+	– Brian Kernighan, The Elements of Programming Style
+
+
 The following guidelines are conducive to clear and readable code that is
 consistent with the style of the rest of the Bonsai Computer System.
 
-0. Use:
+
- - a single line for control flow statements short enough to be easily
+Use
+===
+
+ 0. A single line for control flow statements short enough to be easily
  understood at a glance:
 
 	if !(argc < 0) { usage(program_name); }
 
-This applies to C switch cases, as well.
+ This applies to C switch cases, as well:
 
 	switch (value) { /* aligning stuff to make it easier to read is fine */
 		case possibility: variable = foo;  break;
 		default:          variable = NULL; break;
 	}
 
- - as little nested logic as possible (within reason).
+ 1. Braces in control flow where their inclusion is left optional in C:
- - braces in control flow, when their inclusion is left optional by a
-programming language (in, for example, C).
 
 	if (condition) { statement; }
 
- - empty lines between different kinds of statements:
+ 2. Empty lines between different kinds of statements:
 
 	int t;
 
@@ -40,10 +47,12 @@ programming language (in, for example, C).
 
 	return io;
 
- - compiler options that yield the most useful warnings, such as -Wpedantic in
+ 3. Compiler options that yield the most useful warnings, such as -Wpedantic in
-a lot of C compilers. Fix the warnings, too. See [0].
+ a lot of C compilers. Fix the warnings, too [0].
- - fixed bounds for loops; see [0].
+
- - one more level of indentation and one line per argument, when a function
+ 4. Fixed bounds for loops [0].
+
+ 5. One more level of indentation and one argument per line when a function
  call or statement header is too long to fit on one line:
 
 	let usage = format!(
@@ -51,46 +60,37 @@ call or statement header is too long to fit on one line:
 		argv[0],
 	);
 
- - one more level of indentation than the keyword that initiated a block.
+ 6. One more level of indentation than the keyword that initiated a multi-line
+ block.
 
 	if (condition) {
 		statement;
 		statement;
 	}
 
- - the return value of all non-void functions, or explicitly ignore them (like
+ 7. The return value of all non-void functions, or explicitly ignore them (like
-casting to void in C):
+ casting to void in C) [0]:
 
 	if ((a = malloc(sizeof char)) == NULL) {          /* handle this error */
 		(void)fprintf(stderr, "oh noes!");   /* explicitly ignore this one */
 		return EX_OSERR;       /* ...because the program is exiting anyway */
 	}
 
-See [0].
+ 8. The smallest possible scope for data [0].
 
- - the smallest possible scope for data; see [0].
+ 9. Comments noting all the symbols and macros used from a C header file, next
- - (C) comments noting all the symbols and macros used from a header, next to
+ to its include macro:
-its include macro:
 
 	#include <unistd.h> /* close(2), getopt(3), lseek(2), read(2), write(2),
 	(space-aligned)      * optarg, optind, STDIN_FILENO, STDOUT_FILENO */
 
- - (C) one more level of indentation within switch cases.
+ 10. Spaces in control flow statements, after the keyword and before the
-
-	switch (value) {
-		case possibility:
-			statement;
-		default:
-			statement;
-	}
-
- - (C) spaces in control flow statements, after the keyword and before the
  opening brace:
 
 	for (i = 2; i < argc; ++i) {
 
- - (Cpp) as little of the preprocessor as possible; see [0].
+
- - (Rust) a trailing comma on all arguments or fields that are on their own
+ 11. In Rust, a trailing comma on all arguments or fields that are on their own
  lines:
 
 	return Err(EvaluationError {
@@ -98,8 +98,8 @@ lines:
 		code: EX_DATAERR,
 	})
 
- - (Rust) extern statements after use statements that include standard library
+ 12. In Rust, place extern statements after use statements that include standard
-crates. Group like statements:
+ library crates. Group like statements:
 
 	use std::fs::Path;
 
@@ -109,17 +109,29 @@ crates. Group like statements:
 	use strerror::StrError;
 	use sysexits::{ EX_OSERR, EX_USAGE };
 
- - (Rust) if text is on the same line as a brace, spaces after an opening curly
+ 13. If text is on the same line as a brace, spaces after an opening brace and
-brace and before a closing one:
+ before a closing one:
 
 	use sysexits::{ EX_DATAERR, EX_IOERR, EX_UNAVAILABLE, EX_USAGE };
 
- - (Rust) one more level of indentation within match arms.
+ 14. One more level of indentation for match arms and switch cases.
 
-1. Avoid:
+ 15. Alphabetic sorting, where applicable:
- - function pointers; see [0].
+
- - heap memory allocation; see [0].
+	use std::io::{ BufWriter, Read, Write, stderr, stdin, stdout }
- - too many levels of dereferences; see [0].
+
+ 16. In Rust, use the to_owned() method on string types (str, OsStr, CStr, etc.)
+ and the to_string() method on other types.
+
+
+Avoid
+=====
+
+ 0. Heap memory allocation [0].
+
+ 1. Using too much nested logic (within reason).
+
+ 2. Too many levels of dereferences [0]:
 
 	/* do not do this */
 	for (size_t i = 0; i < sizeof a / sizeof *a; ++i) {
@@ -131,48 +143,92 @@ brace and before a closing one:
 		if (s->id == MATCH) { s->val = 0; }
 	}
 
-2. Do not use:
+ 3. Using C preprocessor macros; the fewer, the better [0].
- - more than the length of one printed page for a function; see [0].
+
- - recursion, as it's complex and can unexpectedly overflow the stack; see [0]
+ 4. The exit(3p) and std::process::exit() functions; returning from the main
-and section 2 of this document.
+ function skips a system call.
- - (C) any language features not in C99.
+
- - (C) do-while loops, as they're unique to the language and confusing for
+
-casual C programmers.
+Do Not Use
- - (C) gotos; use sensible flow control, see [0].
+==========
- - (C) pointer arithmetic, as it tends to be confusing and unnecessary; use
+
+ 0. Function pointers [0].
+
+ 1. More than the length of one printed page for a function [0].
+
+ 2. Recursion, as it’s complex and can unexpectedly overflow the stack [0].
+
+ 3. Any functionality not in the POSIX C specification and language features not
+ in C99.
+
+ 4. Do-while loops, as they’re unique to C and confusing for casual programmers.
+
+ 5. Labels and goto statements; use sensible flow control [0].
+
+ 6. Pointer arithmetic, as it tends to be confusing and unnecessary; use
  index-reference patterns like &p[1] instead of p + 1. &p[n] is the address at
  p + sizeof p * n, not p + n, like pointer arithmetic suggests.
- - (C) struct bitfields in unions, to access certain bits of bigger data types,
+
-as it's poorly defined in the C standards; use bit arithmetic.
+ 7. C struct bitfields in unions, to access certain bits of bigger data types,
- - (C) trigraphs.
+ as it’s poorly defined in the C standards; use bit arithmetic.
- - (Cpp) inclusions in C header files, to prevent multiple file inclusions.
+
- - (Cpp) variables to prevent multiple inclusions of the same file, such as:
+ 8. C trigraphs.
+
+ 9. Inclusions in C header files, to prevent multiple file inclusions.
+
+ 10. C preprocessor variables to prevent multiple inclusions of the same file,
+ such as:
 
 	#ifdef _FILE
 	#define _FILE
 	/* file body */
 	#endif /* ifdef _FILE */
 
-Instead, take the time to ensure other files aren't including the any files
+ Instead, take the time to ensure other files aren’t including the any files
  twice.
 
- - (libc) any functionality not in the latest POSIX or C99.
+ 11. The gets(3p) function from <stdio.h>, as it’s impossible to prevent buffer
- - (libc) gets(3p) from <stdio.h>, as it's impossible to prevent buffer
  overflows when it's used; use fgets(3p) from <stdio.h>.
- - (libc) scanf(3p) from <stdio.h>; see [1].
- - (Make) any functionality not described in make(1p) from the latest POSIX.
 
-2. Keep the following in mind:
+ 12. The scanf(3p) function from <stdio.h> [1].
- - Everyone knows that debugging is twice as hard as writing a program in the
+
-first place. So if you're as clever as you can be when you write it, how will
+ 13. Any functionality not described in the latest POSIX make(1) specification.
-you ever debug it?
+
-	-- Brian Kernighan, in The Elements of Programming Style
+ 14. Macros which panic on failure in Rust (such as the print!() and println!()
+ macros). Use a function and handle any errors. However, do use the eprintln!()
+ macro for error messages. Handling an error for writing an error message is
+ redundant.
+
+
+Usage Text
+==========
+
+This section is adapted from the NetBSD style guide [2].
+
+When programs are invoked incorrectly and in the synopsis of manual pages, uasge
+text should be provided to the user. The following is the format used by this
+project for this purpose:
+
+All optional arguments are to be placed in square brackets (U+005B, U+005D).
+Mutually exclusive arguments can be separated by a vertical line (U+007C).
+Groups of arguments should be specified in alphabetical order in most cases. The
+order of arguments and an example of these rules follows:
+
+ 0. Options with no option arguments.
+ 1. Options with option arguments. Arguments should be specified inside the same
+ square brackets as the options.
+ 3. Non-option arguments.
+
+	"usage: f [-aDde] [-b b_arg] [-m m_arg] req1 req2 [opt1 [opt2]]\n"
+	"usage: f [-a | -b] [-c [-de] [-n number]]\n"
+
 
 References
 ==========
 
 [0] <https://web.eecs.umich.edu/~imarkov/10rules.pdf>
 [1] <http://sekrit.de/webdocs/c/beginners-guide-away-from-scanf.html>
+[2] <http://cvsweb.netbsd.org/bsdweb.cgi/~checkout~/src/share/misc/style>
 
 --
 Copyright © 2024 Emma Tebibyte <emma@tebibyte.media>