From 398428e88322f60100cad3bd51d2ceef7e21608a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Manuel=20Dom=C3=ADnguez?=
 <jose.manuel.dominguez@iwm.fraunhofer.de>
Date: Wed, 1 Sep 2021 17:40:42 +0200
Subject: [PATCH] =?UTF-8?q?Change=20of=20attributes=20for=20added=20indivi?=
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---
 osp/core/cuds.py            | 45 ++++++++++++++++++++++++++++++++++---
 osp/core/ontology/oclass.py |  7 +++---
 osp/core/warnings.py        |  8 +++++++
 3 files changed, 54 insertions(+), 6 deletions(-)
 create mode 100644 osp/core/warnings.py

diff --git a/osp/core/cuds.py b/osp/core/cuds.py
index fe4eee1e..4349c4f1 100644
--- a/osp/core/cuds.py
+++ b/osp/core/cuds.py
@@ -5,9 +5,13 @@
 """
 
 import logging
+from copy import deepcopy
 from uuid import uuid4, UUID
-from typing import Union, List, Iterator, Dict, Any, Optional, Tuple, Iterable
+from typing import Any, Dict, Hashable, Iterable, Iterator, List, Optional, \
+    Tuple, Union
+import rdflib
 from rdflib import URIRef, BNode, RDF, Graph, Literal
+import osp.core.warnings as warning_settings
 from osp.core.namespaces import cuba, from_iri
 from osp.core.ontology.relationship import OntologyRelationship
 from osp.core.ontology.attribute import OntologyAttribute
@@ -179,7 +183,9 @@ def get_attributes(self):
         for s, p, o in self._graph.triples((self.iri, None, None)):
             obj = from_iri(p, raise_error=False)
             if isinstance(obj, OntologyAttribute):
-                result[obj] = o.toPython()
+                value = self._rdflib_5_inplace_modification_prevention_filter(
+                    o.toPython(), obj)
+                result[obj] = value
         return result
 
     def is_a(self, oclass):
@@ -870,7 +876,9 @@ def __getattr__(self, name):
             attr = self._get_attribute_by_argname(name)
             if self.session:
                 self.session._notify_read(self)
-            return self._graph.value(self.iri, attr.iri).toPython()
+            value = self._rdflib_5_inplace_modification_prevention_filter(
+                self._graph.value(self.iri, attr.iri).toPython(), attr)
+            return value
         except AttributeError as e:
             if (  # check if user calls session's methods on wrapper
                 self.is_a(cuba.Wrapper)
@@ -893,6 +901,37 @@ def _get_attribute_by_argname(self, name):
                 return attr
         raise AttributeError(name)
 
+    @staticmethod
+    def _rdflib_5_inplace_modification_prevention_filter(
+            value: Any, attribute: OntologyAttribute) -> Any:
+        if rdflib.__version__ < "6.0.0" and not isinstance(value,
+                                                           Hashable):
+            value = deepcopy(value)
+            if warning_settings.attributes_cannot_modify_in_place:
+                warning_settings.attributes_cannot_modify_in_place = False
+                logger.warning(f"Attribute {attribute} references the mutable "
+                               f"object {value} of type {type(value)}. Please "
+                               f"note that if you modify this object "
+                               f"in-place, the changes will not be reflected "
+                               f"on the cuds object's attribute. \n"
+                               f"For example, executing "
+                               f"`fr = city.City(name='Freiburg', "
+                               f"coordinates=[1, 2]); fr.coordinates[0]=98; "
+                               f"fr.coordinates` would yield `array([1, 2])` "
+                               f"instead of `array([98, 2])`, as you could "
+                               f"expect. Use `fr.coordinates = [98, 2]` "
+                               f"instead, or save the attribute to a "
+                               f"different variable, i.e. `value = "
+                               f"fr.coordinates; value[0] = 98, "
+                               f"fr.coordinates = value`."
+                               f"\n"
+                               f"You will not see this kind of warning again "
+                               f"during this session. You can turn off the "
+                               f"warning by running `import osp.core.warnings "
+                               f"as warning_settings; warning_settings."
+                               f"attributes_cannot_modify_in_place = False`.")
+        return value
+
     def __setattr__(self, name, new_value):
         """Set an attribute.
 
diff --git a/osp/core/ontology/oclass.py b/osp/core/ontology/oclass.py
index d810e4bd..3c0f5683 100644
--- a/osp/core/ontology/oclass.py
+++ b/osp/core/ontology/oclass.py
@@ -1,12 +1,13 @@
 """A class defined in the ontology."""
+
+import logging
 import uuid
 
 import rdflib
+from rdflib import OWL, RDF, RDFS, BNode
 
-from osp.core.ontology.entity import OntologyEntity
 from osp.core.ontology.cuba import rdflib_cuba
-import logging
-from rdflib import OWL, RDFS, RDF, BNode
+from osp.core.ontology.entity import OntologyEntity
 
 logger = logging.getLogger(__name__)
 
diff --git a/osp/core/warnings.py b/osp/core/warnings.py
new file mode 100644
index 00000000..534d51e6
--- /dev/null
+++ b/osp/core/warnings.py
@@ -0,0 +1,8 @@
+"""Configuration of OSP-core warnings."""
+
+attributes_cannot_modify_in_place = True
+"""Warns when a user fetches a mutable attribute of a CUDS object.
+
+For example `fr = city.City(name='Freiburg', coordinates=[1, 2]);
+fr.coordinates`.
+"""