refs.shape

Module nu.domains.shape.refs.shape.

ShapeRef hierarchy: structured container Ref with named-slot navigation.

ShapeRef = shape.MappingForm + StructuredRef MutableShapeRef = shape.MutableMappingForm + ShapeRef ReactiveShapeRef = shape.ReactiveMappingForm + MutableShapeRef

A Shape is structurally a mapping (dict[str, object]). Using the shape-domain MappingForm (which already weaves generic MappingForm + shape CollectionForm) gives all 3 tiers the full mapping surface (keys/values/items/extract/getitem, len, contains) PLUS shape ops (exists/missing/set/erase), without a separate ItemForm in the MRO.

Slot navigation is available two ways:

Attribute: ref.field via __getattr__ (MRO fallback)
Bracket: ref["field"] via __getitem__ override

Both produce a correctly-typed child Ref from the slot definition.

Form composition provides: base: exists(), missing(), extract(), keys(), values(), items(), len(), contains(), [key], .attr mutable: + store(v), erase(), set(k,v), delete(k), update(), ... reactive: + on_change() (generic), on_child_change(), on_children_change(), on_descendants_change() (shape-domain)

MutableShapeRef / ReactiveShapeRef are included.
ReactiveShapeRef composes with shape.ReactiveMappingForm (shape IS a mapping).
wrap* abstract methods from MappingForm raise NotImplementedError on the blueprint. Substrate subclasses fill them in (consistent with MappingRef etc.).

Name	Sort	Call	Meaning
MutableShapeRef	`ref`	`MutableShapeRef(address, shape_type, parent_ref=None, owner_shape=None)`	Mutable structured container Ref.
ReactiveShapeRef	`ref`	`ReactiveShapeRef(address, shape_type, parent_ref=None, owner_shape=None)`	Reactive structured container Ref.
ShapeRef	`ref`	`ShapeRef(address, shape_type, parent_ref=None, owner_shape=None)`	Structured container Ref; slot navigation via attribute or bracket access.

MutableShapeRef

Mutable structured container Ref.

MutableShapeRef(address, shape_type, parent_ref=None, owner_shape=None)

Path nu.domains.shape.MutableShapeRef. Kind Ref, sort ref, cardinality scalar.

Adds: store(v), erase(), set(k,v), delete(k), update(), ... (from shape MutableMappingForm) on top of ShapeRef.

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.shape.ShapeRef:

Call	Builds	Meaning
`a[key]`	`StructuredRef`	Navigate into shape slots via bracket access; mirror of getattr.

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.

Undocumented: example.

ReactiveShapeRef

Reactive structured container Ref.

ReactiveShapeRef(address, shape_type, parent_ref=None, owner_shape=None)

Path nu.domains.shape.ReactiveShapeRef. Kind Ref, sort ref, cardinality scalar.

Adds: on_change() (generic), on_child_change(), on_children_change(), on_descendants_change() (shape-domain, from shape.ReactiveMappingForm) on top of MutableShapeRef.

shape.ReactiveMappingForm is used because a Shape IS a mapping; this provides the full reactive surface (generic on_change + shape tree-aware).

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.shape.ShapeRef:

Call	Builds	Meaning
`a[key]`	`StructuredRef`	Navigate into shape slots via bracket access; mirror of getattr.

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.

Undocumented: example.

ShapeRef

Structured container Ref; slot navigation via attribute or bracket access.

ShapeRef(address, shape_type, parent_ref=None, owner_shape=None)

Path nu.domains.shape.ShapeRef. Kind Ref, sort ref, cardinality scalar.

API: full MappingForm surface: exists(), missing(), extract(), keys(), values(), items(), len(), contains(), [key], .attr from shape MappingForm. _wrap_* methods raise NotImplementedError on the blueprint; substrate subclasses override them.

Methods

`a[key]`

Navigate into shape slots via bracket access; mirror of getattr.

Builds StructuredRef.

Arguments

Name	Type	Default	Meaning
`key`	`object`

Undocumented: example.

Inherited methods

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.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.

Undocumented: example.

refs.shape

MutableShapeRef

ReactiveShapeRef

ShapeRef

a[key]

On this page

`a[key]`