mapping_interactions

Module nu.forms.collections.abc.mapping_interactions.

Mapping interactions.

Reads (Query): Keys, Values, Items, Get, ContainsKey, Copy, ReversedKeys, ReversedValues, ReversedItems, Merge Mutate, yield nothing (Command): DeleteItem, Update (SetItem lives in nu.core.access) Mutate and yield a value (Action): DictPop, PopItem, SetDefault, MergeUpdate

ContainsKey

Test key membership: key in mapping. Yields a bool.

ContainsKey()

Path nu.forms.collections.abc.ContainsKey. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Undocumented: yields, example.

DeleteItem

Delete entry by key: del mapping[key]. Mutates slot 0; returns nothing.

DeleteItem()

Path nu.forms.collections.abc.DeleteItem. Kind Command, sort scalar_command, cardinality void.

Undocumented: yields, example.

DictPop

Pop value by key with optional default: mapping.pop(key, default).

DictPop()

Path nu.forms.collections.abc.DictPop. Kind ScalarAction, sort scalar_action, cardinality scalar.

Mutates slot 0 (removes the entry) and yields the value or default.

Undocumented: yields, example.

Get

Get value from mapping with optional default: mapping.get_item(key, default) or mapping[key].

Get()

Path nu.forms.collections.abc.Get. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Undocumented: yields, example.

Items

Get items view from mapping: mapping.items().

Items()

Path nu.forms.collections.abc.Items. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Undocumented: yields, example.

Keys

Get keys view from mapping: mapping.keys().

Keys()

Path nu.forms.collections.abc.Keys. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Undocumented: yields, example.

Merge

Merge two mappings into a new one: mapping | other. Yields a new dict.

Merge()

Path nu.forms.collections.abc.Merge. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Undocumented: yields, example.

MergeUpdate

In-place merge: mapping |= other. Mutates slot 0 and yields the mapping.

MergeUpdate()

Path nu.forms.collections.abc.MergeUpdate. Kind ScalarAction, sort scalar_action, cardinality scalar.

Python's dict.__ior__ updates in place and returns self, so it both mutates and yields -> Action.

Undocumented: yields, example.

PopItem

Pop arbitrary item: mapping.popitem().

PopItem()

Path nu.forms.collections.abc.PopItem. Kind ScalarAction, sort scalar_action, cardinality scalar.

Mutates slot 0 (removes the entry) and yields the (key, value) tuple.

Undocumented: yields, example.

ReversedItems

(key, value) pairs in reverse insertion order: reversed(mapping.items()).

ReversedItems()

Path nu.forms.collections.abc.ReversedItems. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Scalar-shaped like Items. Same fast-path/fallback contract as ReversedValues -- backends may implement items_reverse() for a single-pass scan; otherwise the runtime uses reversed(obj.items()) (native on dict 3.8+).

Undocumented: yields, example.

ReversedKeys

Reverse-order keys: reversed(mapping). Yields keys in reverse insertion order.

ReversedKeys()

Path nu.forms.collections.abc.ReversedKeys. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Scalar-shaped like Keys -- the thunk returns one iterator handle (Python's reversed(obj) object). Downstream Iter opens that handle into a stream lazily, so islice(m.reversed_keys(), n)` reads only `n items regardless of stream size.

Undocumented: yields, example.

ReversedValues

Values in reverse insertion order: reversed(mapping.values()).

ReversedValues()

Path nu.forms.collections.abc.ReversedValues. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Scalar-shaped like Values -- the thunk returns one iterator handle. Downstream Iter opens the handle into a stream lazily, so islice(m.reversed_values(), n) reads only n values regardless of stream size.

Backend contract: prefers an explicit values_reverse() method on the runtime mapping (fast path, one pass); falls back to reversed(obj.values()) when the mapping doesn't provide one -- that native path works for Python dict (3.8+) and any view whose .values() returns a reversible sequence.

Undocumented: yields, example.

SetDefault

Set default value if key missing: mapping.setdefault(key, default).

SetDefault()

Path nu.forms.collections.abc.SetDefault. Kind ScalarAction, sort scalar_action, cardinality scalar.

Mutates slot 0 (inserts the entry when the key is missing) and yields the value at the key.

Undocumented: yields, example.

Update

Update mapping with another: mapping.update(other). Mutates slot 0; returns nothing.

Update()

Path nu.forms.collections.abc.Update. Kind Command, sort scalar_command, cardinality void.

Undocumented: yields, example.

Values

Get values view from mapping: mapping.values().

Values()

Path nu.forms.collections.abc.Values. Kind ScalarQuery, sort scalar_query, cardinality scalar.

Undocumented: yields, example.