Add PyValue::into_ref and into_ref_with_type.

Author: cthulahoops

vm/src/pyobject.rs

@@ -1578,8 +1578,29 @@ impl PyObject {
 
 // The intention is for this to replace `PyObjectPayload` once everything is
 // converted to use `PyObjectPayload::AnyRustvalue`.
-pub trait PyValue: Any + fmt::Debug {
+pub trait PyValue: Any + fmt::Debug + Sized {
     fn required_type(ctx: &PyContext) -> PyObjectRef;
+
+    fn into_ref(self, ctx: &PyContext) -> PyRef<Self> {
+        PyRef {
+            obj: PyObject::new(self, Self::required_type(ctx)),
+            _payload: PhantomData,
+        }
+    }
+
+    fn into_ref_with_type(self, vm: &mut VirtualMachine, cls: PyClassRef) -> PyResult<PyRef<Self>> {
+        let required_type = Self::required_type(&vm.ctx);
+        if objtype::issubclass(&cls.obj, &required_type) {
+            Ok(PyRef {
+                obj: PyObject::new(self, cls.obj),
+                _payload: PhantomData,
+            })
+        } else {
+            let subtype = vm.to_pystr(&cls.obj)?;
+            let basetype = vm.to_pystr(&required_type)?;
+            Err(vm.new_type_error(format!("{} is not a subtype of {}", subtype, basetype)))
+        }
+    }
 }
 
 impl FromPyObjectRef for PyRef<PyClass> {