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--- research:software:lrp [2016/12/21 15:52] – [Advanced Features] jfabry
+++ research:software:lrp [2016/12/21 16:16] – [Advanced Features] jfabry
@@ Line 209: / Line 209: @@
 === Exit transitions ===
+In a nested machine it is possible to define transitions that go to a state of the parent machine, effectively exiting the nested machine. Such transitions are like normal transactions, except that their keyword is ''exit'' and the destination state should be a state of the parent machine. Note that exit transitions are in fact syntactic sugar.
+A simple example is as follows. As soon as the ''out'' variable is set to ''true'', the nested machine is exit.
+<code>
+(machine root
+	(var out := [false])
+	(state one
+		(machine nested
+			(state onen)
+			(exit goout onen->two)
+			(event goout [out]))
+		(onentry (spawn nested onen))
+	)
+	(state two)
+)
+(spawn root one)
+</code>
 === Eventless transitions ===
+It can become tedious for transitions to need an event as a trigger, since it requires the definition of an event as a separate statement. This is especially tedious when the transition is the only that references that event. To ease this tedium, transitions also accept a block instead of an event name. This block should return true for the transition to trigger.
+Eventless transitions are in fact syntactic sugar: an event is generated and added to the machine, with as action block the block that was specified in the transition, and the transition instead then refers to that event.
 === User interface: Jump to and Transition to ===