delay, eme, stanza_error: Use get_attr!.

src/delay.rs

@@ -30,8 +30,8 @@ impl<'a> TryFrom<&'a Element> for Delay {
         for _ in elem.children() {
             return Err(Error::ParseError("Unknown child in delay element."));
         }
-        let from = elem.attr("from").and_then(|value| value.parse().ok());
+        let from = get_attr!(elem, "from", optional);
-        let stamp = elem.attr("stamp").ok_or(Error::ParseError("Mandatory argument 'stamp' not present in delay element."))?.to_owned();
+        let stamp = get_attr!(elem, "stamp", required);
         let data = match elem.text().as_ref() {
             "" => None,
             text => Some(text.to_owned()),

src/eme.rs

@@ -28,8 +28,8 @@ impl<'a> TryFrom<&'a Element> for ExplicitMessageEncryption {
         for _ in elem.children() {
             return Err(Error::ParseError("Unknown child in encryption element."));
         }
-        let namespace = elem.attr("namespace").ok_or(Error::ParseError("Mandatory argument 'namespace' not present in encryption element."))?.to_owned();
+        let namespace = get_attr!(elem, "namespace", required);
-        let name = elem.attr("name").and_then(|value| value.parse().ok());
+        let name = get_attr!(elem, "name", optional);
         Ok(ExplicitMessageEncryption {
             namespace: namespace,
             name: name,

src/message_correct.rs

@@ -27,11 +27,8 @@ impl<'a> TryFrom<&'a Element> for Replace {
         for _ in elem.children() {
             return Err(Error::ParseError("Unknown child in replace element."));
         }
-        let id = match elem.attr("id") {
+        let id = get_attr!(elem, "id", required);
-            Some(id) => id.to_owned(),
+        Ok(Replace { id })
-            None => return Err(Error::ParseError("No 'id' attribute present in replace.")),
-        };
-        Ok(Replace { id: id })
     }
 }
 
@@ -73,7 +70,7 @@ mod tests {
             Error::ParseError(string) => string,
             _ => panic!(),
         };
-        assert_eq!(message, "No 'id' attribute present in replace.");
+        assert_eq!(message, "Required attribute 'id' missing.");
     }
 
     #[test]

src/stanza_error.rs

@@ -158,11 +158,8 @@ impl<'a> TryFrom<&'a Element> for StanzaError {
             return Err(Error::ParseError("This is not an error element."));
         }
 
-        let type_ = elem.attr("type")
+        let type_ = get_attr!(elem, "type", required);
-                        .ok_or(Error::ParseError("Error must have a 'type' attribute."))?
+        let by = get_attr!(elem, "by", optional);
-                        .parse()?;
-        let by = elem.attr("by")
-                     .and_then(|by| by.parse().ok());
         let mut defined_condition = None;
         let mut texts = BTreeMap::new();
         let mut other = None;
@@ -172,7 +169,7 @@ impl<'a> TryFrom<&'a Element> for StanzaError {
                 for _ in child.children() {
                     return Err(Error::ParseError("Unknown element in error text."));
                 }
-                let lang = child.attr("xml:lang").unwrap_or("").to_owned();
+                let lang = get_attr!(elem, "xml:lang", default);
                 if texts.insert(lang, child.text()).is_some() {
                     return Err(Error::ParseError("Text element present twice for the same xml:lang."));
                 }
@@ -256,7 +253,7 @@ mod tests {
             Error::ParseError(string) => string,
             _ => panic!(),
         };
-        assert_eq!(message, "Error must have a 'type' attribute.");
+        assert_eq!(message, "Required attribute 'type' missing.");
 
         let elem: Element = "<error xmlns='jabber:client' type='coucou'/>".parse().unwrap();
         let error = StanzaError::try_from(&elem).unwrap_err();