FIX support both instance and class level methods in _AvailableIfDescriptor.__get__ (scikit-learn#20623)

harupy · web-flow · commit f2f8b52ee26f · 2021-07-28T18:17:37.000+02:00
diff --git a/sklearn/utils/metaestimators.py b/sklearn/utils/metaestimators.py
@@ -110,8 +110,12 @@ def __get__(self, obj, owner=None):
                     f" {repr(self.attribute_name)}"
                 )
 
-        # lambda, but not partial, allows help() to work with update_wrapper
-        out = lambda *args, **kwargs: self.fn(obj, *args, **kwargs)  # noqa
+            # lambda, but not partial, allows help() to work with update_wrapper
+            out = lambda *args, **kwargs: self.fn(obj, *args, **kwargs)  # noqa
+        else:
+            # This makes it possible to use the decorated method as an unbound method,
+            # for instance when monkeypatching.
+            out = lambda *args, **kwargs: self.fn(*args, **kwargs)  # noqa
         # update the docstring of the returned function
         update_wrapper(out, self.fn)
         return out
diff --git a/sklearn/utils/tests/test_metaestimators.py b/sklearn/utils/tests/test_metaestimators.py
@@ -104,3 +104,10 @@ def test_available_if_docstring():
 def test_available_if():
     assert hasattr(AvailableParameterEstimator(), "available_func")
     assert not hasattr(AvailableParameterEstimator(available=False), "available_func")
+
+    # This is a non regression test for:
+    # https://github.com/scikit-learn/scikit-learn/issues/20614
+    # to make sure that decorated functions can be used as an unbound method,
+    # for instance when monkeypatching.
+    est = AvailableParameterEstimator()
+    AvailableParameterEstimator.available_func(est)
