class poll_engine :
?extra_match:exn -> bool -> (Unixqueue.operation * float) list -> Unixqueue.event_system ->
This engine waits until one of the passed operations can be
carried out, or until one of the operations times out.
In these cases, the state of the engine changes to
`Done ev, where
ev is the corresponding event.
The argument list enumerates the operations to watch for. For every operation there may be a positive timeout value, or a negative number to indicate that no timeout is specified.
After one event has been caught, the engine terminates operation.
restart can be called to activate it again (with the
same event condition, and the same notification list). See the
restart for possible problems.
extra_match: This function is called when an
Extraevent is found. If the function returns
truefor the argument exception of
Extra, the event is caught; otherwise it is rejected.
method restart :
unit -> unit
Activate the engine again when it is already in a final state. This method violates the engine protocol, and should be used with care; it is not allowed to leave a final state.
The notification lists are kept, but note that observers often detach when final states are reached. This may cause problems.
method group :
Returns the group the engine is member of