LazyDict

class LazyDict(load_function, eval_function=None, *args, **kwargs)

Bases: dict[K, V], Generic[K, V]

Dictionary that supports lazy loading and optional lazy value evaluation.

Parameters:

• load_function (Callable[[], dict[K, V] | Iterable[tuple[K, V]]]) – Callable returning either a dict or an iterable of (key, value) pairs.

• eval_function (Callable[[V], V] | None) – Optional callable applied to values on first access (per key).

• args (Any)

• kwargs (Any)

Example

>>> def load(): return {"a": "2 + 2"}
>>> def evaluate(expr): return eval(expr)
>>> d = LazyDict(load, evaluate)
>>> d["a"]
4

__init__(load_function, eval_function=None, *args, **kwargs)

Parameters:

• load_function (Callable[[], dict[K, V] | Iterable[tuple[K, V]]])

• eval_function (Callable[[V], V] | None)

• args (Any)

• kwargs (Any)

Return type:

None

Methods

__init__(load_function[, eval_function])
clear()
copy()
fromkeys(iterable[, value])	Create a new dictionary with keys from iterable and values set to value.
get(key[, default])	Return the value for key if key is in the dictionary, else default.
items()
keys()
pop(k[,d])	If the key is not found, return the default if given; otherwise, raise a KeyError.
popitem()	Remove and return a (key, value) pair as a 2-tuple.
reload()	Reload the dictionary using the original load function.
setdefault(key[, default])	Insert key with a value of default if key is not in the dictionary.
update([E, ]**F)	If E is present and has a .keys() method, then does: for k in E.keys(): D[k] = E[k] If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k]
values()

keys() → a set-like object providing a view on D's keys

values() → an object providing a view on D's values

items() → a set-like object providing a view on D's items

get(key, default=None)

Return the value for key if key is in the dictionary, else default.

Parameters:

• key (K)

• default (V | None)

Return type:

V | None

reload()

Reload the dictionary using the original load function.

Clears existing values and evaluation state, then loads fresh data.

Return type:

None

clear() → None.  Remove all items from D.

copy() → a shallow copy of D

classmethod fromkeys(iterable, value=None, /)

Create a new dictionary with keys from iterable and values set to value.

pop(k[, d]) → v, remove specified key and return the corresponding value.

If the key is not found, return the default if given; otherwise, raise a KeyError.

popitem()

Remove and return a (key, value) pair as a 2-tuple.

Pairs are returned in LIFO (last-in, first-out) order. Raises KeyError if the dict is empty.

setdefault(key, default=None, /)

Insert key with a value of default if key is not in the dictionary.

Return the value for key if key is in the dictionary, else default.

update([E, ]**F) → None.  Update D from mapping/iterable E and F.

If E is present and has a .keys() method, then does: for k in E.keys(): D[k] = E[k] If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k]