constantdict

class constantdict.constantdict

An immutable dictionary that does not allow modifications after creation. This class behaves mostly like a dict, but with the following differences.

Additional methods compared to dict:

__hash__() → int

Return a hash of this constantdict. This constantdict is hashable if all of its keys and values are hashable. Once computed, the hash is cached.

mutate() → constantdictmutation[K, V]

Return a mutable copy of this constantdict as a constantdictmutation.

Run constantdictmutation.finish() to convert back to an immutable constantdict.

Note

Based on the immutables.Map API.

>>> cd = constantdict(a=1, b=2)
>>> cd_mut = cd.mutate()
>>> cd_mut["a"] = 10
>>> del cd_mut["b"]
>>> cd_new = cd_mut.finish()
>>> cd_new
constantdict({'a': 10})
>>> cd  # unchanged
constantdict({'a': 1, 'b': 2})

Methods that return a modified copy of the constantdict:

set(key: K, value: Any) → constantdict[K, V]

Return a new constantdict with the item at key set to val.

setdefault(key: K, default: V | None = None) → constantdict[K, V]

Return a new constantdict with the item at key set to default if key is not in the dictionary.

Return a reference to itself if key is present.

Note

Based on the frozendict API.

delete(key: K) → constantdict[K, V]

Return a new constantdict without the item at key.

Raise a KeyError if key is not present.

update(other: dict[K, V]) → constantdict[K, V]

Return a new constantdict with updated items from other.

Note

In contrast to dict.update(), this method does not modify the original constantdict, but creates a new, updated copy.

>>> cd = constantdict(a=1, b=2)
>>> cd_new = cd.update({"a": 10, "c": 3})
>>> cd_new
constantdict({'a': 10, 'b': 2, 'c': 3})
>>> cd
constantdict({'a': 1, 'b': 2})

discard(key: K) → constantdict[K, V]

Return a new constantdict without the item at the given key.

Return a reference to itself if the key is not present.

Note

Based on the pyrsistent.PMap API.

Deleted methods compared to dict (these raise an AttributeError when called):

__delitem__()

__setitem__()

clear()

popitem()

pop()

class constantdict.constantdictmutation

A mutable dictionary that can be converted back to a constantdict without copying. This class behaves exactly like a dict, except for the additions mentioned below.

Additional method compared to dict:

finish() → constantdict[K, V]

Convert this object to an immutable version of itself.

>>> cd_mut = constantdict(a=1, b=2).mutate()
>>> cd_mut["a"] = 12
>>> cd = cd_mut.finish()
>>> cd
constantdict({'a': 12, 'b': 2})

It can also be used as a context manager:

>>> with constantdict(a=1, b=2).mutate() as cd_mut:
...     cd_mut["a"] = 10
...     del cd_mut["b"]
...     cd_new = cd_mut.finish()
>>> cd_new
constantdict({'a': 10})

class constantdict.constantdictuncachedhash

A constantdict that does not cache its hash value. This is useful when the dictionary contains items that are not immutable and whose hash value might therefore change.

mutate() → constantdictuncachedhashmutation[K, V]

Return a mutable copy of this constantdict as a constantdictuncachedhashmutation.

Run constantdictuncachedhashmutation.finish() to convert back to an immutable constantdict.

class constantdict.constantdictuncachedhashmutation

A mutable dictionary that can be converted back to a constantdictuncachedhash without copying. This class behaves exactly like a dict, except for one additional method mentioned below.

Additional method compared to dict:

finish() → constantdictuncachedhash[K, V]

Convert this object to an immutable version of itself.

Type classes

class constantdict.K

A type representing a key in a constantdict. Must be hashable.

class constantdict.V

A type representing a value in a constantdict.