Kamaelia.Util.Comparator

• component Comparator

• Comparing two data sources
  • Example Usage
  • How does it work?

Comparing two data sources

The Comparator component tests two incoming streams to see if the items they contain match (pass an equality test).

Example Usage

Compares contents of two files and prints "MISMATCH!" whenever one is found:

class DetectFalse(component):
    def main(self):
        while 1:
            yield 1
            if self.dataReady("inbox"):
                if not self.recv("inbox"):
                    print "MISMATCH!"

Graphline( file1   = RateControlledFileReader(filename="file 1", ...),
           file2   = RateControlledFileReader(filename="file 2", ...),
           compare = Comparator(),
           fdetect = DetectFalse(),
           output  = ConsoleEchoer(),
           linkages = {
               ("file1","outbox") : ("compare","inA"),
               ("file2","outbox") : ("compare","inB"),
               ("compare", "outbox") : ("fdetect", "inbox"),
               ("fdetect", "outbox") : ("output", "inbox"),
           },
         ).run()

How does it work?

The component simply waits until there is data ready on both its "inA" and "inB" inboxes, then takes an item from each and compares them. The result of the comparison is sent to the "outbox" outbox.

If data is available at neither, or only one, of the two inboxes, then the component will wait indefinitely until data is available on both.

If a producerFinished or shutdownMicroprocess message is received on the "control" inbox, then a producerFinished message is sent out of the "signal" outbox and the component terminates.

The comparison is done by the combine() method. This method returns the result of a simple equality test of the two arguments.

You could always subclass this component and reimplement the combine() method to perform different functions (for example, an 'adder').

---

Kamaelia.Util.Comparator.Comparator

class Comparator(Axon.Component.component)

Comparator() -> new Comparator component.

Compares items received on "inA" inbox with items received on "inB" inbox. For each pair, outputs True if items compare equal, otherwise False.

Inboxes

• control : NOT USED
• inbox : NOT USED
• inB : Source 'B' of items to compare
• inA : Source 'A' of items to compare

Outboxes

• outbox : Result of comparison
• signal : NOT USED

Methods defined here

combine(self, valA, valB)

Returns result of (valA == valB)

Reimplement this method to change the type of comparison from equality testing.

mainBody(self)

Main loop body.