Unable to pickle or deepcopy Domains, Actions, Problems

[James-Oswald]

Subject of the issue

The cache hashing mechanism appears to break my ability to deepcopy or pickle any of the core objects.

Your environment

• OS: Red Hat Enterprise Linux release 8.7
• Python version: 3.9.13
• Package Version 3.1

Steps to reproduce

Minimally reproducible example for domains, same issue with actions and problems

import copy
import pickle
import traceback

from pddl.parser.domain import DomainParser

domain_str = """
    (define (domain test)
        (:requirements :typing)
        (:types t1)
        (:constants c1 - t1)
        (:predicates  (p1 ?v1 - t1))
        (:action a1
        :parameters (?v - t1)
        :effect (c1))
)"""

domain = DomainParser()(domain_str)

#Deep copy domains
try:
    copy.deepcopy(domain)
except Exception:
    print(traceback.format_exc())

#Pickle domains
try:
    pickle.dumps(domain)
except Exception:
    print(traceback.format_exc())

Expected behaviour

I should get a deepcopied/pickled domain/action/problem without any errors occurring.

Actual behaviour

All fails with KeyError: 'hash' in the `d.pop("hash")oncache_hash.py` line 56.

[marcofavorito]

Thank you @James-Oswald for the issue. This is indeed an unintended behaviour.

[James-Oswald]

Thanks for the speedy fix!