Actions

Actions execute at lifecycle points.

Lifecycle Action Types

• on_entry(action)
• on_entry_from(trigger, action)
• on_exit(action)
• on_activate(action)
• on_deactivate(action)

Sync and Async Actions

Both sync and async actions are supported.

• Sync action example:

def on_entry(transition):
    print("entered", transition.destination)

• Async action example:

async def on_entry_async(transition):
    ...

await sm.fire_async(Trigger.X)

If async actions are involved, calling fire(...) raises TypeError.

Action Signatures

Action wrappers support callables that consume transition context and/or trigger args.

Recommended signatures:

• Entry/internal action with transition context and all fired args tuple:

def action(transition, args):
    ...

• Exit action:

def on_exit(transition):
    ...

• Activate/deactivate action:

def on_activate():
    ...

For robustness, keep action signatures explicit and simple.

on_entry_from

on_entry_from(trigger, action) runs only when entry was caused by that trigger.

Useful for parameterized workflows where one state has multiple incoming transitions.