lrhn
commented
1 year ago Unix permissions is the only use for octal numerals that I'm aware of. It seems like something that could be fixed by using an abstraction, rather than adding a language feature with no other practical uses. Will probably be more readable than 0o754 to readers too.
Take:
const x = 1;
const w = 2;
const r = 4;
const rw = r | w;
const rx = r | x;
const wx = w | x;
const rwx = r | w | x;
int perm({int u = 0, int f = 0, int o = 0, int user = 0, int group = 0, int others = 0}) =>
((u | user) << 6) | ((g | group) << 3) | (o | others);so you can just write perm(u: rw, g: r, o: w), and not use (low-readability) number literals at all.
Or use perm(u: 7, g: 5, o: 5) if you prefer the numbers to the names.
Use the longer names if you like that better. Add extra parameters for special bits. Or parse a string.
Or just introduce a helper like oct(7, 5, 5) like:
int oct(int d1, [int? d2, int? d3, int? d4, int? d5]) {
int ensureOctal(int d) => d >= 0 && d <= 7 ? d : (throw ArgumentError.value(d, null, "not octal digit"));
var value = ensureOctal(d1);
if (d2 != null) {
value = (value << 3) | d2;
if (d3 != null) {
value = (value << 3) | d3;
// etc.
}
}
return value;
}(If I were to design a Posix files system API in the near future, I'd use an inline class on an int for permissions, rather than a plain int.)
nex3
mateusfccp
munificent
Related to https://github.com/dart-lang/language/issues/581, I'd also like to see octal literals using the common
0o123syntax. The lack of these actually caused a security issue for Dart Sass recently (see https://github.com/google/dart_cli_pkg/pull/109) because we incorrectly converted Unix permissions bits from octal to decimal and ended up creating world-writable executables under certain circumstances.