Add `cause()` method to `Error` type.

Returns the underlying error type, if any.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/error.rs b/src/error.rs
index 57d636a..b26a21d 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -26,6 +26,13 @@ impl error::Error for Error {
             Error::NotmuchError(ref e) => e.description(),
         }
     }
+
+    fn cause(&self) -> Option<&error::Error> {
+        match *self {
+            Error::IoError(ref e) => Some(e),
+            Error::NotmuchError(ref e) => Some(e),
+        }
+    }
 }
 
 impl error::FromError<io::Error> for Error {