init

src/lib.rs

@@ -0,0 +1,57 @@
+//! The Rear error wrapper
+
+use std::error::Error;
+use std::fmt::{Display, Formatter, Result as FmtResult};
+use std::result::Result as StdResult;
+
+/// A `std::result::Result` wrapper that simply has a `Rear` as the error.
+pub type Result<T> = StdResult<T, Rear>;
+
+/// A `Rear` is simply a message paired with the error.
+#[derive(Debug)]
+pub struct Rear {
+	error: Box<dyn Error>,
+	message: String,
+}
+
+impl Rear {
+	/// Return a reference to the error.
+	pub fn error(&self) -> &Box<dyn Error> {
+		&self.error
+	}
+
+	/// Return the message as a `&str`.
+	pub fn message(&self) -> &str {
+		&self.message
+	}
+
+	/// Create a new `Rear` from an error implementing `std::error::Error` with
+	/// a message from anything that implementes `Into<String>`.
+	pub fn new<S: Into<String>>(error: Box<dyn Error>, message: S) -> Self {
+		let message = message.into();
+
+		Self {
+			error,
+			message,
+		}
+	}
+}
+
+impl Display for Rear {
+	fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult {
+		if ! self.message.is_empty() {
+			write!(f, "{}", self.error)
+		} else {
+			write!(f, "{}\n{}", &self.message, &self.error)
+		}
+	}
+}
+
+impl From<Box<dyn Error>> for Rear {
+	fn from(error: Box<dyn Error>) -> Self {
+		Self {
+			error: error,
+			message: String::new(),
+		}
+	}
+}