A workaround for Python's missing frozen-dict type? [duplicate]

Answer 1

You can try ordered dict or look on these answers:

• What would a "frozen dict" be?
• Immutable dictionary, only use as a key for another dictionary
• How to create an immutable dictionary in python?

and there is even a package on PyPI: https://pypi.python.org/pypi/frozendict

You can also simply convert dict to tuples(sorted(your_dict.items())) and then use as a hash.

UPD: as mentioned in comments, OrderedDict is unhashable. My bad, it is really should not be hashable since it is mutable.

Answer 2

I've found a nice workaround for this problem, which is building a frozenset containing the dictionary items:

EDIT: this answer was written before/around the time keeping dictionary's insertion order became a feature. The provided code will lose the ordering, which is irrelevant for Python < 3.6.

>>> a = {'key1' : 'val1', 'key2' : 'val2'}
>>> b = frozenset(a.items())
>>> frozenset_restored_to_dict = dict(b)
>>> frozenset_restored_to_dict
{'key2': 'val2', 'key1': 'val1'}

As can be seen in the code, b is a frozenset, which is immutable and hashable, and can be totally restored to be a regular dictionary like a.