refs.prog

Module nustd.kv.refs.prog.

Virtuals-substrate ref for a stored Nu program.

ProgramRef is a leaf whose stored value is python source text and whose value interface is Program. That makes a program a first-class slot on a Shape:

class App(Shape):
    job = ProgramRef.slot()

run(App.job.set(SOURCE), ctx)
run(App.job.run(), ctx)

No codec, unlike its neighbours in std. DecimalRef and friends override _lift / set because their domain type is not what the substrate can hold; a program is source text on both sides, so the stored form is the domain form and there is nothing to translate. The mixin is carrying an interface, not a representation.

MRO note: ItemRef comes first, Program second. That order decides whose _compile and whose declared sort win, and getting it backwards is silent - see the class docstring.

Name	Sort	Call	Meaning
ProgramRef	`ref`	`ProgramRef(address, parent_ref=None, owner_shape=None)`	A Nu program stored as source text in a KV leaf, with the Program verbs.

ProgramRef

A Nu program stored as source text in a KV leaf, with the Program verbs.

ProgramRef(address, parent_ref=None, owner_shape=None)

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

Reading it yields the source verbatim, the same as any str leaf. What the Program surface adds is the ability to turn that stored text into a tree and run it, so a program becomes a value a shape can hold, write and replace at run time.

Notes

No codec: source text is both the stored form and the value form, unlike the std refs that translate between the two.
The base order is load-bearing. ItemRef first makes the class a ref that reads storage; with Program first the passthrough would win and the ref would yield its parent instead of the stored value, silently, with no fabric touch recorded.
Construction errors surface when the stored source is loaded or run, not when it is written, so bad source stores fine.

Example

class App(Shape):
    job = ProgramRef.slot()
run(App.job.set(SOURCE), ctx)
run(App.job.run(), ctx)

Inherited methods

From nu.domains.shape.forms.item.ReactiveItemForm:

Call	Builds	Meaning
`.on_change()`	`OnPrimitiveChange`	Subscribe to changes on this leaf.

From nu.domains.shape.forms.item.MutableItemForm:

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

From nu.domains.shape.forms.item.ItemForm:

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

From nu.prog.forms.Program:

Call	Builds	Meaning
`.load(entry='out', scope=None, filename='<nu program>', brace=<UNSET>, rewrite=None)`	`Nu`	Construct the term without running it.
`.run(entry='out', scope=None, filename='<nu program>', brace=<UNSET>, rewrite=None, on_error=None)`	`Nu`	Construct the term and drive it.

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.prog

ProgramRef

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