new example using EventGenerator added

dream/simulation/Examples/BalancingABuffer.py

+from dream.simulation.imports import Machine, Queue, Exit, Part, EventGenerator  
+from dream.simulation.Globals import runSimulation, G
+
+# method to check if the buffer is starving and refill it
+def balanceQueue(buffer, refillLevel=1):
+    objectQueue=buffer.getActiveObjectQueue()
+    numInQueue=len(objectQueue)
+    print '-'*50
+    print 'at time=', G.env.now
+    if numInQueue==0:
+        print 'buffer is starving, I will bring 5 parts'
+        for i in range(refillLevel):
+            partId='P'+str(G.numOfParts)
+            partName='Part'+str(G.numOfParts)
+            P=Part(partId, partName, currentStation=buffer)       
+            objectQueue.append(P)
+            G.numOfParts+=1
+        # send a signal to the buffer that it can dispose an Entity
+        buffer.canDispose.succeed(G.env.now)
+    else:
+        print 'buffer has', numInQueue, 'parts. No need to bring more'
+
+#define the objects of the model 
+Q=Queue('Q1','Queue', capacity=float('inf'))
+M=Machine('M1','Machine', processingTime={'distributionType':'Fixed','mean':6})
+E=Exit('E1','Exit')
+EV=EventGenerator('EV', 'EntityCreator', start=0, stop=float('inf'), interval=20,method=balanceQueue, 
+                  argumentDict={'buffer':Q, 'refillLevel':5})  
+
+G.numOfParts=0
+   
+#define predecessors and successors for the objects    
+Q.defineRouting(successorList=[M])
+M.defineRouting(predecessorList=[Q],successorList=[E])
+E.defineRouting(predecessorList=[M])
+
+def main():
+    # add all the objects in a list
+    objectList=[Q,M,E,EV]  
+    # set the length of the experiment  
+    maxSimTime=100.0
+    # call the runSimulation giving the objects and the length of the experiment
+    runSimulation(objectList, maxSimTime)
+
+    #print the results
+    print '='*50
+    print "the system produced", E.numOfExits, "parts"
+    working_ratio = (M.totalWorkingTime/maxSimTime)*100
+    print "the total working ratio of the Machine is", working_ratio, "%"
+    return {"parts": E.numOfExits,
+          "working_ratio": working_ratio}
+
+if __name__ == '__main__':
+    main()
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