implement ToPyObject and IntoPyObject for PyErr

src/err.rs

@@ -12,7 +12,7 @@ use object::PyObject;
 use objects::{PyObjectRef, PyType, exc};
 use instance::Py;
 use typeob::PyTypeObject;
-use conversion::{ToPyObject, ToBorrowedObject};
+use conversion::{ToPyObject, IntoPyObject, ToBorrowedObject};
 
 /// Defines a new exception type.
 ///
@@ -360,7 +360,7 @@ impl PyErr {
     /// Retrieves the exception instance for this error.
     /// This method takes `mut self` because the error might need
     /// to be normalized in order to create the exception instance.
-    pub fn instance(mut self, py: Python) -> PyObject {
+    fn instance(mut self, py: Python) -> PyObject {
         &self.normalize(py);
         match self.pvalue {
             PyErrValue::Value(ref instance) => instance.clone_ref(py),
@@ -425,6 +425,29 @@ impl std::fmt::Debug for PyErr {
     }
 }
 
+impl IntoPyObject for PyErr {
+
+    fn into_object(self, py: Python) -> PyObject {
+        self.instance(py)
+    }
+}
+
+impl ToPyObject for PyErr {
+
+    fn to_object(&self, py: Python) -> PyObject {
+        let err = self.clone_ref(py);
+        err.instance(py)
+    }
+}
+
+impl<'a> IntoPyObject for &'a PyErr {
+
+    fn into_object(self, py: Python) -> PyObject {
+        let err = self.clone_ref(py);
+        err.instance(py)
+    }
+}
+
 /// Converts `PyDowncastError` to Python `TypeError`.
 impl std::convert::From<PyDowncastError> for PyErr {
     fn from(_err: PyDowncastError) -> PyErr {

src/object.rs

@@ -283,6 +283,14 @@ impl IntoPyObject for PyObject
     }
 }
 
+impl<'a> IntoPyObject for &'a PyObject
+{
+    #[inline]
+    fn into_object(self, py: Python) -> PyObject {
+        unsafe {PyObject::from_borrowed_ptr(py, self.as_ptr())}
+    }
+}
+
 impl<'a> FromPyObject<'a> for PyObject
 {
     #[inline]

src/objects/bytearray.rs

@@ -99,7 +99,7 @@ mod test {
 
         let none = py.None();
         if let Err(err) = PyByteArray::from(py, &none) {
-            assert!(py.is_instance::<exc::TypeError, _>(&err.instance(py)).unwrap())
+            assert!(err.is_instance::<exc::TypeError>(py));
         } else {
             panic!("error");
         }

src/objects/exc_impl.rs

@@ -122,7 +122,7 @@ mod test {
 
         let d = PyDict::new(py);
         d.set_item("socket", py.import("socket").unwrap()).unwrap();
-        d.set_item("exc", err.instance(py)).unwrap();
+        d.set_item("exc", err).unwrap();
 
         py.run("assert isinstance(exc, socket.gaierror)", None, Some(d)).unwrap();
     }