Impl Display and Error for Error

src/error.rs

@@ -1,4 +1,4 @@
-use std::result;
+use std::{error, fmt, io, result};
 
 use url;
 use hyper;
@@ -6,21 +6,56 @@ use hyper;
 /// Errors that can occur during authentication flow.
 #[derive(Debug)]
 pub enum Error {
+    Io(io::Error),
     Url(url::ParseError),
     Hyper(hyper::Error),
+    Todo,
 }
 
 /// Result type returned from authentication flow methods.
 pub type Result<T> = result::Result<T, Error>;
 
-impl From<url::ParseError> for Error {
-    fn from(err: url::ParseError) -> Error {
-        Error::Url(err)
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Error::Io(ref err) => write!(f, "{}", err),
+            Error::Url(ref err) => write!(f, "{}", err),
+            Error::Hyper(ref err) => write!(f, "{}", err),
+            Error::Todo => write!(f, "Not implemented!"),
+        }
     }
 }
 
-impl From<hyper::Error> for Error {
-    fn from(err: hyper::Error) -> Error {
-        Error::Hyper(err)
+impl error::Error for Error {
+    fn description(&self) -> &str {
+        match *self {
+            Error::Io(_) => "OAuth2 IO error",
+            Error::Url(_) => "OAuth2 URL error",
+            Error::Hyper(_) => "OAuth2 Hyper error",
+            Error::Todo => "OAuth2 not implemented error",
         }
     }
+
+    fn cause(&self) -> Option<&error::Error> {
+        match *self {
+            Error::Io(ref err) => Some(err),
+            Error::Url(ref err) => Some(err),
+            Error::Hyper(ref err) => Some(err),
+            _ => None,
+        }
+    }
+}
+
+macro_rules! impl_from {
+    ($v:path, $t:ty) => {
+        impl From<$t> for Error {
+            fn from(err: $t) -> Error {
+                $v(err)
+            }
+        }
+    }
+}
+
+impl_from!(Error::Io, io::Error);
+impl_from!(Error::Url, url::ParseError);
+impl_from!(Error::Hyper, hyper::Error);