refs.dictshape

Module nustd.mem.refs.dictshape.

Dict shapes dict reference: mapping of homogeneous shapes.

Key descent (ref[k]) is the blueprint's __getitem__: it returns a ShapeRef at the key with this ref as parent_ref. The value shape type is passed to the blueprint as item_shape_type.

Name	Sort	Call	Meaning
ShapesDictRef	`ref`	`ShapesDictRef(address, shape_type, key_type, key_value_type, parent_ref=None, owner_shape=None)`	A keyed collection of one Shape's records, stored as a dict of dicts.

ShapesDictRef

A keyed collection of one Shape's records, stored as a dict of dicts.

ShapesDictRef(address, shape_type, key_type, key_value_type, parent_ref=None, owner_shape=None)

Path nustd.mem.ShapesDictRef. Kind Ref, sort ref, cardinality scalar.

Subscripting descends: ref[k] is a ShapeRef at that key holding the value Shape, so users["ada"].name is a path down to a leaf and nothing is read until the whole chain runs. The mapping calls on the ref itself act on the outer dict.

Notes

Values are plain dicts, so a record is added by writing a dict, not a Shape instance.
Writing through a key creates the outer dict and the record on the way down; the whole-container calls (keys, update, ...) instead do nothing while the slot is absent.

Example

class User(nu.Shape):
    name = nustd.mem.StrRef.slot()
class Team(nu.Shape):
    users = nustd.mem.ShapesDictRef.slot(User)
data = {}
ctx = nu.Context().bind(dict, data, Team)
_ = nu.run(Team.users["ada"].name.set("Ada"), ctx)
data

{'users': {'ada': {'name': 'Ada'}}}

Inherited methods

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.shapes_mapping.ShapesMappingRef:

Call	Builds	Meaning
`a[key]`	`ItemResultT`	Navigate to the child ShapeRef 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.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.dictshape

ShapesDictRef

On this page