refs.dict

Module nustd.kv.refs.dict.

Virtuals mapping reference: key-value container backed by a virtuals View.

Name	Sort	Call	Meaning
DictRef	`ref`	`DictRef(address, value_type, key_type, key_value_type, value_value_type, view_type, parent_ref=None, owner_shape=None)`	A mapping slot in KV storage, decomposed into a child per key.

DictRef

A mapping slot in KV storage, decomposed into a child per key.

DictRef(address, value_type, key_type, key_value_type, value_value_type, view_type, parent_ref=None, owner_shape=None)

Path nustd.kv.DictRef. Kind Ref, sort ref, cardinality scalar.

Every value lives at its own address under the slot, so keys can be read, written and watched one at a time without touching the rest. Key and value types are fixed at declaration; keys default to str.

Notes

Ops run against the live View, so len, contains and keys are answered by storage rather than by materializing the mapping.
Subscripting yields a leaf ref of the declared value type, which is what makes ref[k].set(...) and ref[k].on_change() possible.
A key that has never been written reads as EMPTY; use get_item with a default when a fallback is wanted.
The key may itself be an expression or a ref, so a lookup can be computed at run time.
PrimitiveDictRef is the other choice: one opaque blob, no per-key addresses, but heterogeneous contents.

Example

class Portfolio(Shape):
    metadata = DictRef.slot(str)
run(Portfolio.metadata.set_item("owner", "gor"), ctx)
run(Portfolio.metadata["owner"], ctx)

Inherited methods

From nu.forms.collections.abc.mapping.ReactiveMappingForm:

Call	Builds	Meaning
`.on_change()`	`object`	Subscribe to any change on this mapping slot.

From nu.forms.collections.abc.mapping.MutableMappingForm:

Call	Builds	Meaning
`.set_item(key, value)`	`Any`	Set the value at key, inserting the key if it's missing: mapping[key] = value.
`.del_item(key)`	`Any`	Delete the entry at key: del mapping[key].
`.update(other)`	`Any`	Write other's entries into self, in place: mapping.update(other).
`.pop(key, default=None)`	`ValueResultT`	Remove key and yield its value, or default if key is missing.
`.popitem()`	`ValueResultT`	Remove and yield an arbitrary (key, value) pair: mapping.popitem().
`.setdefault(key, default=None)`	`ValueResultT`	Value at key, inserting default there first if key is missing.
`.merge_update(other)`	`CollectionResultT`	Merge other into self in place, and yield self: mapping \|= other.
`.clear()`	`Any`	Remove all entries: mapping.clear().

From nu.domains.shape.refs.mapping.MappingRef:

Call	Builds	Meaning
`a[key]`	`ItemResultT`	Navigate to the child Ref at `key`, with self as parent.

From nu.forms.collections.abc.mapping.MappingForm:

Call	Builds	Meaning
`.keys()`	`CollectionResultT`	All keys of the mapping: mapping.keys().
`.values()`	`CollectionResultT`	All values of the mapping: mapping.values().
`.items()`	`CollectionResultT`	All (key, value) pairs of the mapping: mapping.items().
`.get_item(key, default=None)`	`ValueResultT`	Value at key, falling back to default: mapping.get_item(key, default).
`.copy()`	`CollectionResultT`	Shallow copy of self: mapping.copy().
`.reversed_keys()`	`CollectionResultT`	Keys in reverse insertion order: reversed(mapping).
`.reversed_values()`	`CollectionResultT`	Values in reverse insertion order: reversed(mapping.values()).
`.reversed_items()`	`CollectionResultT`	(key, value) pairs in reverse insertion order: reversed(mapping.items()).
`.merge(other)`	`CollectionResultT`	Self and other merged into a new mapping: mapping \| other.

From nu.forms.collections.abc.collection.CollectionForm:

Call	Builds	Meaning
`.extract()`	`object`	Materialise the full subtree rooted at self.

From nu.forms.collections.abc.sized.SizedForm:

Call	Builds	Meaning
`.len()`	`Int`	Length of self.

From nu.forms.collections.abc.iterable.IterableForm:

Call	Builds	Meaning
`iter(a)`	`Iterator[ElementT]`	Open self into a lazy iterator stream (Python's `iter`).

From nu.forms.collections.abc.container.ContainerForm:

Call	Builds	Meaning
`.contains(item)`	`Bool`	Whether item is a member of self.

From nu.domains.shape.forms.collection.ReactiveCollectionForm:

Call	Builds	Meaning
`.on_child_change(address)`	`OnChildChange`	Observe changes at a specific child address.
`.on_children_change()`	`OnChildrenChange`	Observe changes across all direct children.
`.on_descendants_change()`	`OnDescendantsChange`	Observe changes across descendants matching `pattern`.

From nu.domains.shape.forms.collection.MutableCollectionForm:

Call	Builds	Meaning
`.set(value)`	`SetCmd`	Build a `SetCmd`.
`.erase()`	`Erase`	Build an `Erase`.
`.init(value)`	`IfDo`	Set `value` iff the collection is currently missing.

From nu.domains.shape.forms.collection.CollectionForm:

Call	Builds	Meaning
`.exists()`	`Exists`	Build an `Exists` query.
`.missing()`	`Missing`	Build a `Missing` query.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.is_invalid()`	`Bool`	True if this Form yields the INVALID sentinel.
`.is_sentinel()`	`Bool`	True if this Form yields either sentinel (EMPTY or INVALID).
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.not_invalid()`	`Bool`	True if this Form does not yield INVALID.

refs.dict

DictRef

On this page