Copy explicit_no_refs from ClassPrivate to InstancePrivate (#876)

param/parameterized.py

@@ -1511,7 +1511,9 @@ def __set__(self, obj, val):
             else:
                 # When setting a Parameter before calling super.
                 if not isinstance(obj._param__private, _InstancePrivate):
-                    obj._param__private = _InstancePrivate()
+                    obj._param__private = _InstancePrivate(
+                        explicit_no_refs=type(obj)._param__private.explicit_no_refs
+                    )
                 _old = obj._param__private.values.get(name, self.default)
                 obj._param__private.values[name] = val
         self._post_setter(obj, val)
@@ -4040,6 +4042,7 @@ class _InstancePrivate:
         'syncing',
         'watchers',
         'values',
+        'explicit_no_refs',
     ]
 
     def __init__(
@@ -4051,8 +4054,10 @@ def __init__(
         params=None,
         watchers=None,
         values=None,
+        explicit_no_refs=None
     ):
         self.initialized = initialized
+        self.explicit_no_refs = [] if explicit_no_refs is None else explicit_no_refs
         self.syncing = set()
         if parameters_state is None:
             parameters_state = {
@@ -4132,7 +4137,9 @@ def __init__(self, **params):
         # _InstancePrivate namespace over the _ClassPrivate namespace
         # (see Parameter.__set__) so we shouldn't override it here.
         if not isinstance(self._param__private, _InstancePrivate):
-            self._param__private = _InstancePrivate()
+            self._param__private = _InstancePrivate(
+                explicit_no_refs=type(self)._param__private.explicit_no_refs
+            )
 
         # Skip generating a custom instance name when a class in the hierarchy
         # has overriden the default of the `name` Parameter.
@@ -4191,12 +4198,13 @@ def __setstate__(self, state):
 
         During this process the object is considered uninitialized.
         """
-        self._param__private = _InstancePrivate()
+        explicit_no_refs = type(self)._param__private.explicit_no_refs
+        self._param__private = _InstancePrivate(explicit_no_refs=explicit_no_refs)
         self._param__private.initialized = False
 
         _param__private = state.get('_param__private', None)
         if _param__private is None:
-            _param__private = _InstancePrivate()
+            _param__private = _InstancePrivate(explicit_no_refs=explicit_no_refs)
 
         # When making a copy the internal watchers have to be
         # recreated and point to the new instance