Closure Zones

A Closure zone packages a block of nodes as a value. The closure can be passed around, through node groups or bundles, and evaluated later with an Evaluate Closure node.

Use the @closure_zone decorator. The function’s parameters become the closure’s inputs, and its return values become the closure’s outputs.

@closure_zone
def scale(x: float, factor: float = 2.0):
    return x * factor

@tree("Closure")
def closure_tree(value: float):
    closure = scale()                          # A Closure socket
    return scale.evaluate(closure, value, 3.0) # Evaluate it

Calling the decorated function inside a tree creates the zone and returns its Closure socket. scale.evaluate(closure, ...) adds an Evaluate Closure node with the same inputs and outputs as scale, and passes the remaining arguments to its inputs.

The closure must be created before it is evaluated, so the zone’s outputs are known.

A tree can take a closure as an input with the Closure annotation:

@tree("Apply")
def apply(value: float, operation: Closure):
    return scale.evaluate(operation, value, 2.0)