Fixup Result-returning encode method

src/io/frame.rs

@@ -242,7 +242,7 @@ pub trait Codec {
     /// This method will encode `msg` into the byte buffer provided by `buf`.
     /// The `buf` provided is an internal buffer of the `Framed` instance and
     /// will be written out when possible.
-    fn encode(&mut self, msg: Self::Out) -> Result<Vec<u8>, io::Error>;
+    fn encode(&mut self, msg: Self::Out, buf: &mut Vec<u8>) -> io::Result<()>;
 }
 
 /// A unified `Stream` and `Sink` interface to an underlying `Io` object, using
@@ -319,7 +319,7 @@ impl<T: Io, C: Codec> Sink for Framed<T, C> {
             }
         }
 
-        self.wr = self.codec.encode(item).unwrap();
+        try!(self.codec.encode(item, &mut self.wr));
         Ok(AsyncSink::Ready)
     }
 

tests/line-frames.rs

@@ -28,8 +28,9 @@ impl Codec for LineCodec {
         Ok(buf.drain_to(amt))
     }
 
-    fn encode(&mut self, item: EasyBuf, into: &mut Vec<u8>) {
+    fn encode(&mut self, item: EasyBuf, into: &mut Vec<u8>) -> io::Result<()> {
         into.extend_from_slice(item.as_slice());
+        Ok(())
     }
 }