[ENH] option to return BaseObject.get_param_names in the same order as in the __init__

skbase/base/_base.py

@@ -58,6 +58,7 @@
 from collections import defaultdict
 from copy import deepcopy
 from typing import List
+from warnings import warn
 
 from skbase._exceptions import NotFittedError
 from skbase.base._pretty_printing._object_html_repr import _object_html_repr
@@ -205,17 +206,43 @@
                 )
         return parameters
 
+    # todo 0.10.0: changed sort default to False
+    # update docstring, and remove warning
     @classmethod
-    def get_param_names(cls):
+    def get_param_names(cls, sort=None):
         """Get object's parameter names.
 
+        Parameters
+        ----------
+        sort : bool, default=True
+            Whether to return the parameter names sorted in alphabetical order (True),
+            or in the order they appear in the class ``__init__`` (False).
+
         Returns
         -------
         param_names: list[str]
-            Alphabetically sorted list of parameter names of cls.
+            List of parameter names of cls.
+            If ``sort=False``, in same order as they appear in the class ``__init__``.
+            If ``sort=True``, alphabetically ordered.
         """
+        if sort is None:
+            sort = True
+            warn(
+                "In scikit-base BaseObject.get_param_names, the default of parameter"
+                " 'sorted' will change from True to False in 0.10.0. "
+                "This will change the order of the output, returning the parameters"
+                " in the order they appear in the class __init__, "
+                "rather than alphabetically ordered. "
+                "To retain previous behaviour in direct calls, "
+                "set 'sort=True'. To silence this warning, set 'sorted' to "
+                "either True or False.",
+                FutureWarning,
+            )
+
         parameters = cls._get_init_signature()
-        param_names = sorted([p.name for p in parameters])
+        param_names = [p.name for p in parameters]
+        if sorted:
+            param_names = sorted(param_names)
         return param_names
 
     @classmethod
@@ -586,7 +613,7 @@
             `create_test_instance` uses the first (or only) dictionary in `params`
         """
         params_with_defaults = set(cls.get_param_defaults().keys())
-        all_params = set(cls.get_param_names())
+        all_params = set(cls.get_param_names(sort=False))
         params_without_defaults = all_params - params_with_defaults
 
         # if non-default parameters are required, but none have been found, raise error

skbase/tests/test_base.py

@@ -706,16 +706,21 @@ def test_get_init_signature_raises_error_for_invalid_signature(
         fixture_invalid_init._get_init_signature()
 
 
+@pytest.mark.parametrize("sorted", [True, False])
 def test_get_param_names(
     fixture_object: Type[BaseObject],
     fixture_class_parent: Type[Parent],
     fixture_class_parent_expected_params: Dict[str, Any],
+    sorted: bool,
 ):
     """Test that get_param_names returns list of string parameter names."""
-    param_names = fixture_class_parent.get_param_names()
-    assert param_names == sorted([*fixture_class_parent_expected_params])
+    param_names = fixture_class_parent.get_param_names(sort=sorted)
+    if sorted:
+        assert param_names == sorted([*fixture_class_parent_expected_params])
+    else:
+        assert param_names == [*fixture_class_parent_expected_params]
 
-    param_names = fixture_object.get_param_names()
+    param_names = fixture_object.get_param_names(sort=sorted)
     assert param_names == []