frozendict

frozendict is an immutable wrapper around dictionaries that implements the complete mapping interface. It can be used as a drop-in replacement for dictionaries where immutability is desired.

Of course, this is python, and you can still poke around the object's internals if you want.

The frozendict constructor mimics dict, and all of the expected interfaces (iter, len, repr, hash, getitem) are provided. Note that a frozendict does not guarantee the immutability of its values, so the utility of hash method is restricted by usage.

The only difference is that the copy() method of frozendict takes variable keyword arguments, which will be present as key/value pairs in the new, immutable copy.

Example shell usage:

from frozendict import frozendict

fd = frozendict({ 'hello': 'World' })

print fd
# <frozendict {'hello': 'World'}>

print fd['hello']
# 'World'

print fd.copy(another='key/value')
# <frozendict {'hello': 'World', 'another': 'key/value'}>