implement fmt::Display for Error

src/errors.rs

@@ -1,5 +1,5 @@
 use super::{Class, ToRuby};
-use std::{any};
+use std::{any, fmt};
 use sys::{VALUE, SPRINTF_TO_S, c_string, rb_eRuntimeError, rb_raise};
 
 #[derive(Copy, Clone, Debug)]
@@ -43,6 +43,21 @@ impl Error {
     }
 }
 
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.message {
+            ErrorMessage::Static(c_string) => {
+                use ::std::ffi::CStr;
+                write!(f, "{}", unsafe { CStr::from_ptr(c_string) }.to_str().unwrap())
+            },
+            ErrorMessage::Dynamic(value) => {
+                use super::FromRuby;
+                write!(f, "{}", String::from_ruby_unwrap(value))
+            }
+        }
+    }
+}
+
 unsafe impl Send for Error {}
 unsafe impl Sync for Error {}