Adds a pair of notifiers which get invoked before and after the closure callback, respectively.
This is typically used to protect the extra arguments for the duration of the callback. See watch_closure for an example of marshal guards.
| this |
a Closure |
| pre_marshal_data |
data to pass to |
| post_marshal_data |
data to pass to |
| post_marshal_notify |
a function to call after the closure callback |
| pre_marshal_notify |
a function to call before the closure callback |