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Documentation related to python3-frozenlist
Package: python3-frozenlist
Description: list-like structure which implements collections.abc.MutableSequence
`frozenlist.FrozenList` is a list-like structure which implements
`collections.abc.MutableSequence`. The list is mutable until `FrozenList.freeze`
is called, after which list modifications raise `RuntimeError`:
>>> from frozenlist import FrozenList
>>> fl = FrozenList([17, 42])
>>> fl.append('spam')
>>> fl.append('Vikings')
>>> fl
<FrozenList(frozen=False, [17, 42, 'spam', 'Vikings'])>
>>> fl.freeze()
>>> fl
<FrozenList(frozen=True, [17, 42, 'spam', 'Vikings'])>
>>> fl.frozen
True
>>> fl.append("Monty")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "frozenlist/_frozenlist.pyx", line 97, in frozenlist._frozenlist.FrozenList.append
self._check_frozen()
File "frozenlist/_frozenlist.pyx", line 19, in frozenlist._frozenlist.FrozenList._check_frozen
raise RuntimeError("Cannot modify frozen list.")
RuntimeError: Cannot modify frozen list.
FrozenList is also hashable, but only when frozen. Otherwise it also throws a RuntimeError:
>>> fl = FrozenList([17, 42, 'spam'])
>>> hash(fl)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "frozenlist/_frozenlist.pyx", line 111, in frozenlist._frozenlist.FrozenList.__hash__
raise RuntimeError("Cannot hash unfrozen list.")
RuntimeError: Cannot hash unfrozen list.
>>> fl.freeze()
>>> hash(fl)
3713081631934410656
>>> dictionary = {fl: 'Vikings'} # frozen fl can be a dict key
>>> dictionary
{<FrozenList(frozen=True, [1, 2])>: 'Vikings'}
Homepage: https://github.com/aio-libs/frozenlist
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