This notebook serves to document an error when reloading the owlready2 module due to the access to nonexisting dictionary entries.

import importlib
import owlready2 as owl2

# this works:

# createing dummy values for some dictionary entries
owl2.owl_world._props["Property"] = None
owl2.owl_world._props["ObjectProperty"] = None
owl2.owl_world._props["DatatypeProperty"] = None
owl2.owl_world._props["FunctionalProperty"] = None
owl2.owl_world._props["InverseFunctionalProperty"] = None
owl2.owl_world._props["TransitiveProperty"] = None
owl2.owl_world._props["SymmetricProperty"] = None
owl2.owl_world._props["AsymmetricProperty"] = None
owl2.owl_world._props["ReflexiveProperty"] = None
owl2.owl_world._props["IrreflexiveProperty"] = None
owl2.owl_world._props["AnnotationProperty"] = None

importlib.reload(owl2)

<module 'owlready2' from '/media/workcard/workstickdir/RST/expertise_system/ontologie_experimente/owlready2_repo_parent/owlready2/__init__.py'>

# this works not (KeyError):
importlib.reload(owl2)

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
Input In [3], in <module>
      1 # this works not (key error):
----> 2 importlib.reload(owl2)

File ~/miniconda3/envs/base38/lib/python3.8/importlib/__init__.py:169, in reload(module)
    167 if spec is None:
    168     raise ModuleNotFoundError(f"spec not found for the module {name!r}", name=name)
--> 169 _bootstrap._exec(spec, module)
    170 # The module may have replaced itself in sys.modules!
    171 return sys.modules[name]

File <frozen importlib._bootstrap>:604, in _exec(spec, module)

File <frozen importlib._bootstrap_external>:783, in exec_module(self, module)

File <frozen importlib._bootstrap>:219, in _call_with_frames_removed(f, *args, **kwds)

File /media/workcard/workstickdir/RST/expertise_system/ontologie_experimente/owlready2_repo_parent/owlready2/__init__.py:117, in <module>
    114 LOADING.__exit__()
    116 # Not real property
--> 117 del owl_world._props["Property"]
    118 del owl_world._props["ObjectProperty"]
    119 del owl_world._props["DatatypeProperty"]

KeyError: 'Property'