diff --git a/pyglove/core/symbolic/contextual_object.py b/pyglove/core/symbolic/contextual_object.py
index 892a1ad..a856a87 100644
--- a/pyglove/core/symbolic/contextual_object.py
+++ b/pyglove/core/symbolic/contextual_object.py
@@ -46,7 +46,7 @@ class A(pg.ContextualObject):
 """
 
 import threading
-from typing import Annotated, Any, ContextManager, Dict, Optional, Type
+from typing import Annotated, Any, ClassVar, ContextManager, Dict, Optional, Type
 from pyglove.core import utils as pg_utils
 from pyglove.core.symbolic import base
 from pyglove.core.symbolic import inferred as pg_inferred
@@ -109,13 +109,13 @@ def foo(a):
   """
 
   # Override __repr__ format to use inferred values when available.
-  __repr_format_kwargs__ = dict(
+  __repr_format_kwargs__: ClassVar[Dict[str, Any]] = dict(
       compact=True,
       use_inferred=True,
   )
 
   # Override __str__ format to use inferred values when available.
-  __str_format_kwargs__ = dict(
+  __str_format_kwargs__: ClassVar[Dict[str, Any]] = dict(
       compact=False,
       verbose=False,
       use_inferred=True,
diff --git a/pyglove/core/symbolic/object.py b/pyglove/core/symbolic/object.py
index 65bf0bf..d3e78eb 100644
--- a/pyglove/core/symbolic/object.py
+++ b/pyglove/core/symbolic/object.py
@@ -28,6 +28,14 @@
 from pyglove.core.symbolic import flags
 
 
+if sys.version_info >= (3, 11):
+  _dataclass_transform = typing.dataclass_transform
+else:
+  def _dataclass_transform():
+    return lambda cls: cls
+
+
+@_dataclass_transform()
 class ObjectMeta(abc.ABCMeta):
   """Meta class for pg.Object."""
 
@@ -153,6 +161,8 @@ def _infer_fields_from_annotations(cls) -> List[pg_typing.Field]:
       if attr_name == '__kwargs__':
         # __kwargs__ is speical annotation for enabling keyword arguments.
         key = pg_typing.StrKey()
+        if typing.get_origin(attr_annotation) is typing.ClassVar:
+          attr_annotation = typing.get_args(attr_annotation)[0]
       elif not attr_name.isupper() and not attr_name.startswith('_'):
         key = pg_typing.ConstStrKey(attr_name)
       else:
diff --git a/pyglove/core/utils/formatting.py b/pyglove/core/utils/formatting.py
index b133b62..6aeff31 100644
--- a/pyglove/core/utils/formatting.py
+++ b/pyglove/core/utils/formatting.py
@@ -17,7 +17,7 @@
 import enum
 import io
 import sys
-from typing import Any, Callable, ContextManager, Dict, List, Optional, Sequence, Set, Tuple
+from typing import Any, Callable, ClassVar, ContextManager, Dict, List, Optional, Sequence, Set, Tuple
 from pyglove.core.utils import thread_local
 
 
@@ -55,10 +55,12 @@ class Formattable(metaclass=abc.ABCMeta):
   """
 
   # Additional format keyword arguments for `__str__`.
-  __str_format_kwargs__ = dict(compact=False, verbose=True)
+  __str_format_kwargs__: ClassVar[Dict[str, Any]] = dict(
+      compact=False, verbose=True
+  )
 
   # Additional format keyword arguments for `__repr__`.
-  __repr_format_kwargs__ = dict(compact=True)
+  __repr_format_kwargs__: ClassVar[Dict[str, Any]] = dict(compact=True)
 
   @abc.abstractmethod
   def format(self,