raise_

Module nu.core.flows.raise_.

Raise: raise an exception at run time.

Nu's Sort taxonomy has no bare "effect" sort. A Command must declare a mutation (the command_has_write law), and raising touches no fabric -- so Raise sits in the Control seat instead. A Control is a Flow that composes Commands under Query parameters; Raise takes a single value parameter (the message) and no body slots. That leaves the sort semantics clean:

• Sort.CONTROL is a subsort of Sort.FLOW, so a Raise slots into any Flow body position (an IfDo body, a Sequential arm, ...).
• The param slot (slot 0, the msg) is yielding -- satisfies control_param_yielders.
• No body slots, so flow_body_is_mutator is trivially satisfied.

Wire-up:

• exc_cls is a plain Python class captured in the atom's payload -- the exception type is a structural detail of the tree, not run-time data.
• msg is any Nu expression yielding a value (typically a str). If the message resolves to a sentinel (EMPTY / INVALID) the raise is skipped -- "the condition is not yet ready", not "raise something obscured".

Raise

Raise exc_cls(msg) at run time.

Raise(msg, exc_cls=RuntimeError)

Path nu.core.flows.Raise. Kind Control, sort control, cardinality void. Arity 2 (1 required).

Arguments

Yields

Never returns normally; raises exc_cls(msg) or skips.

Notes

• A leaf Control: one param slot (the msg), no body slots, so flow_body_is_mutator is trivially satisfied.
• exc_cls is a plain Python class captured in the payload, not a child - the exception type is a structural detail of the tree, not run-time data.
• If msg resolves to EMPTY or INVALID the raise is skipped: "the condition is not yet ready", not "raise something obscured".

Example

try:
    nu.run(nu.raise_(ValueError, "boom"))
except ValueError as e:
    print(e)

boom

raise_

Build a Raise node. Wrap in IfDo to gate.

flows.raise_(exc_cls, msg)

Path nu.core.flows.raise_. Defined on nu.core.flows.raise_, bound as a function. Builds Raise.

Arguments

Undocumented: example.