[Feature] Fix DType casting lazy init

test/test_transforms.py

@@ -2259,12 +2259,6 @@ def test_double2float(self, keys, keys_inv, device):
             )
             action_spec = double2float.transform_input_spec(input_spec)
             assert action_spec.dtype == torch.float
-
-        elif len(keys) == 1:
-            observation_spec = BoundedTensorSpec(0, 1, (1, 3, 3), dtype=torch.double)
-            observation_spec = double2float.transform_observation_spec(observation_spec)
-            assert observation_spec.dtype == torch.float
-
         else:
             observation_spec = CompositeSpec(
                 {
@@ -2274,7 +2268,7 @@ def test_double2float(self, keys, keys_inv, device):
             )
             observation_spec = double2float.transform_observation_spec(observation_spec)
             for key in keys:
-                assert observation_spec[key].dtype == torch.float
+                assert observation_spec[key].dtype == torch.float, key
 
     @pytest.mark.parametrize("device", get_default_devices())
     @pytest.mark.parametrize(
@@ -2326,6 +2320,7 @@ def test_single_env_no_inkeys(self):
             base_env.state_spec[key] = spec.to(torch.float64)
         if base_env.action_spec.dtype == torch.float32:
             base_env.action_spec = base_env.action_spec.to(torch.float64)
+        check_env_specs(base_env)
         env = TransformedEnv(
             base_env,
             DoubleToFloat(),
@@ -2335,6 +2330,8 @@ def test_single_env_no_inkeys(self):
         for spec in env.state_spec.values(True, True):
             assert spec.dtype == torch.float32
         assert env.action_spec.dtype != torch.float64
+        assert env.transform.in_keys == env.transform.out_keys
+        assert env.transform.in_keys_inv == env.transform.out_keys_inv
         check_env_specs(env)
 
     def test_single_trans_env_check(self, dtype_fixture):  # noqa: F811

torchrl/envs/transforms/rlhf.py

@@ -2,7 +2,7 @@
 #
 # This source code is licensed under the MIT license found in the
 # LICENSE file in the root directory of this source tree.
-from copy import deepcopy
+from copy import copy, deepcopy
 
 import torch
 from tensordict import TensorDictBase, unravel_key
@@ -93,24 +93,22 @@ def __init__(
         if in_keys is None:
             in_keys = self.DEFAULT_IN_KEYS
         if out_keys is None:
-            out_keys = in_keys
-        if not isinstance(in_keys, list):
-            in_keys = [in_keys]
-        if not isinstance(out_keys, list):
-            out_keys = [out_keys]
-        if not is_seq_of_nested_key(in_keys) or not is_seq_of_nested_key(out_keys):
+            out_keys = copy(in_keys)
+        super().__init__(in_keys=in_keys, out_keys=out_keys)
+        if not is_seq_of_nested_key(self.in_keys) or not is_seq_of_nested_key(
+            self.out_keys
+        ):
             raise ValueError(
-                f"invalid in_keys / out_keys:\nin_keys={in_keys} \nout_keys={out_keys}"
+                f"invalid in_keys / out_keys:\nin_keys={self.in_keys} \nout_keys={self.out_keys}"
             )
-        if len(in_keys) != 1 or len(out_keys) != 1:
+        if len(self.in_keys) != 1 or len(self.out_keys) != 1:
             raise ValueError(
-                f"Only one in_key/out_key is allowed, got in_keys={in_keys}, out_keys={out_keys}."
+                f"Only one in_key/out_key is allowed, got in_keys={self.in_keys}, out_keys={self.out_keys}."
             )
-        super().__init__(in_keys=in_keys, out_keys=out_keys)
         # for convenience, convert out_keys to tuples
-        self.out_keys = [
+        self._out_keys = [
             out_key if isinstance(out_key, tuple) else (out_key,)
-            for out_key in self.out_keys
+            for out_key in self._out_keys
         ]
 
         # update the in_keys for dispatch etc