Termination

examples/basic.rs

@@ -14,11 +14,11 @@ pub fn main() {
     match parse_int_or_return_error_exitcode("foo") {
         Ok(i) => {
             println!("Parsed: {}", i);
-            process::exit(exitcode::OK);
+            process::exit(exitcode::OK.into());
         },
         Err(code) => {
             writeln!(stderr(), "Parse error.  Exiting with code: {}", code).unwrap();
-            process::exit(code);
+            process::exit(code.into());
         }
     }
 }

src/lib.rs

@@ -11,82 +11,101 @@
 //! ```
 
 /// Alias for the numeric type that holds system exit codes.
-pub type ExitCode = i32;
+#[derive(Copy, Clone, PartialEq, Eq)]
+pub struct ExitCode(i32);
+
+impl From<ExitCode> for i32 {
+    fn from(ec: ExitCode) -> i32 {
+        ec.0
+    }
+}
+
+impl std::fmt::Display for ExitCode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+impl std::process::Termination for ExitCode {
+    fn report(self) -> std::process::ExitCode {
+        std::process::ExitCode::from(self.0 as u8) // safe because our highest exit code fits in u8
+    }
+}
 
 /// Successful exit
-pub const OK: ExitCode = 0;
+pub const OK: ExitCode = ExitCode(0);
 
 /// The command was used incorrectly, e.g., with the
 /// wrong number of arguments, a bad flag, a bad syntax
 /// in a parameter, etc.
-pub const USAGE: ExitCode = 64;
+pub const USAGE: ExitCode = ExitCode(64);
 
 /// The input data was incorrect in some way.  This
 /// should only be used for user's data and not system
 /// files.
-pub const DATAERR: ExitCode = 65;
+pub const DATAERR: ExitCode = ExitCode(65);
 
 /// An input file (not a system file) did not exist or
 /// was not readable.  This could also include errors
 /// like "No message" to a mailer (if it cared to
 /// catch it).
-pub const NOINPUT: ExitCode = 66;
+pub const NOINPUT: ExitCode = ExitCode(66);
 
 /// The user specified did not exist.  This might be
 /// used for mail addresses or remote logins.
-pub const NOUSER: ExitCode = 67;
+pub const NOUSER: ExitCode = ExitCode(67);
 
 /// The host specified did not exist.  This is used in
 /// mail addresses or network requests.
-pub const NOHOST: ExitCode = 68;
+pub const NOHOST: ExitCode = ExitCode(68);
 
 /// A service is unavailable.  This can occur if a
 /// support program or file does not exist. This can also
 /// be used as a catchall message when something you
 /// wanted to do doesn't work, but you don't know why.
-pub const UNAVAILABLE: ExitCode = 69;
+pub const UNAVAILABLE: ExitCode = ExitCode(69);
 
 /// An internal software error has been detected.  This
 /// should be limited to non-operating system related
 /// errors as possible.
-pub const SOFTWARE: ExitCode = 70;
+pub const SOFTWARE: ExitCode = ExitCode(70);
 
 /// An operating system error has been detected.  This
 /// is intended to be used for such things as "cannot
 /// fork", "cannot create pipe", or the like.  It
 /// includes things like getuid returning a user that
 /// does not exist in the passwd file.
-pub const OSERR: ExitCode = 71;
+pub const OSERR: ExitCode = ExitCode(71);
 
 /// Some system file (e.g., /etc/passwd, /var/run/utmp,
 /// etc.) does not exist, cannot be opened, or has some
 /// sort of error (e.g., syntax error).
-pub const OSFILE: ExitCode = 72;
+pub const OSFILE: ExitCode = ExitCode(72);
 
 /// A (user specified) output file cannot be created.
-pub const CANTCREAT: ExitCode = 73;
+pub const CANTCREAT: ExitCode = ExitCode(73);
 
 /// An error occurred while doing I/O on some file.
-pub const IOERR: ExitCode = 74;
+pub const IOERR: ExitCode = ExitCode(74);
 
 /// Temporary failure, indicating something that is not
 /// really an error.  In sendmail, this means that a
 /// mailer (e.g.) could not create a connection, and
 /// the request should be reattempted later.
-pub const TEMPFAIL: ExitCode = 75;
+pub const TEMPFAIL: ExitCode = ExitCode(75);
 
 /// The remote system returned something that was
 /// "not possible" during a protocol exchange.
-pub const PROTOCOL: ExitCode = 76;
+pub const PROTOCOL: ExitCode = ExitCode(76);
 
 /// You did not have sufficient permission to perform
 /// the operation.  This is not intended for file system
 /// problems, which should use `NOINPUT` or `CANTCREAT`,
 /// but rather for higher level permissions.
-pub const NOPERM: ExitCode = 77;
+pub const NOPERM: ExitCode = ExitCode(77);
 
 /// Something was found in an unconfigured or misconfigured state.
-pub const CONFIG: ExitCode = 78;
+pub const CONFIG: ExitCode = ExitCode(78);
 
 /// Check if exit code given by `code` is successful
 ///