DOC Ensures that if_delegate_has_method passes numpydoc validation (#…

…24633)

Co-authored-by: Guillaume Lemaitre <g.lemaitre58@gmail.com>
Co-authored-by: Thomas J. Fan <thomasjpfan@gmail.com>

sklearn/tests/test_docstrings.py

@@ -13,7 +13,6 @@
 
 FUNCTION_DOCSTRING_IGNORE_LIST = [
     "sklearn.utils.extmath.fast_logdet",
-    "sklearn.utils.metaestimators.if_delegate_has_method",
 ]
 FUNCTION_DOCSTRING_IGNORE_LIST = set(FUNCTION_DOCSTRING_IGNORE_LIST)
 

sklearn/utils/metaestimators.py

@@ -142,22 +142,27 @@ def _check(self, obj):
 
 # TODO(1.3) remove
 def if_delegate_has_method(delegate):
-    """Create a decorator for methods that are delegated to a sub-estimator
-
-    This enables ducktyping by hasattr returning True according to the
-    sub-estimator.
+    """Create a decorator for methods that are delegated to a sub-estimator.
 
     .. deprecated:: 1.3
         `if_delegate_has_method` is deprecated in version 1.1 and will be removed in
         version 1.3. Use `available_if` instead.
 
+    This enables ducktyping by hasattr returning True according to the
+    sub-estimator.
+
     Parameters
     ----------
     delegate : str, list of str or tuple of str
         Name of the sub-estimator that can be accessed as an attribute of the
         base object. If a list or a tuple of names are provided, the first
         sub-estimator that is an attribute of the base object will be used.
 
+    Returns
+    -------
+    callable
+        Callable makes the decorated method available if the delegate
+        has a method with the same name as the decorated method.
     """
     if isinstance(delegate, list):
         delegate = tuple(delegate)