Allow custom data in errors to be displayed

libimagerror/src/error_gen.rs

@@ -118,7 +118,10 @@ macro_rules! generate_custom_error_types {
 
             fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
                 try!(write!(fmt, "[{}]", self.err_type));
-                Ok(())
+                match self.custom_data {
+                    Some(ref c) => write!(fmt, "{}", c),
+                    None => Ok(()),
+                }
             }
 
         }
@@ -215,6 +218,13 @@ macro_rules! generate_error_types {
     ) => {
         #[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Copy)]
         pub struct SomeNotExistingTypeWithATypeNameNoOneWillEverChoose {}
+
+        impl Display for SomeNotExistingTypeWithATypeNameNoOneWillEverChoose {
+            fn fmt(&self, _: &mut Formatter) -> Result<(), FmtError> {
+                Ok(())
+            }
+        }
+
         generate_custom_error_types!($name, $kindname,
                                      SomeNotExistingTypeWithATypeNameNoOneWillEverChoose,
                                      $($kind => $string),*);
@@ -241,6 +251,12 @@ mod test {
         pub othr: i64,
     }
 
+    impl Display for CustomData {
+        fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
+            Ok(())
+        }
+    }
+
     generate_error_imports!();
 
     #[allow(dead_code)]

libimagstore/src/error.rs

@@ -23,6 +23,12 @@ use std::convert::From;
 #[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd, Copy)]
 pub struct CustomErrorData {}
 
+impl Display for CustomErrorData {
+    fn fmt(&self, _: &mut Formatter) -> Result<(), FmtError> {
+        Ok(()) // Do nothing here, we don't need to print smth
+    }
+}
+
 generate_custom_error_types!(StoreError, StoreErrorKind, CustomErrorData,
     ConfigurationError      => "Store Configuration Error",
     ConfigTypeError         => "Store configuration type error",