class poll_engine :?extra_match:exn -> bool -> (Unixqueue.operation * float) list -> Unixqueue.event_system ->object..end
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.
The method restart can be called to activate it again (with the
same event condition, and the same notification list). See the
description of restart for possible problems.
extra_match : This function is called when an Extra event is
found. If the function returns true for the argument exception
of Extra, the event is caught; otherwise it is rejected.method restart : unit -> unitActivate 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 : Unixqueue.groupReturns the group the engine is member of
