My solution for UncleBob's Mark IV CoffeeMaker - Retrospective

Part 5: Rear-view mirror.
So it's the end of the flashback.. for anyone who lasted this far. I've the design all coded out and it works. So let's have a look at the design that we ended up with. Might be a good side-by-side compare with the first post in this series.
Final touch-ups that I did,
  • renamed SensorObserver to ObservableCoffeeMakerDevice.. long name but it is an internal class so there.
  • Also I renamed some event-handler in CoffeeMaker in the name of readability and all that is good. On_WarmerPlateStatusChangedAfterBrew >> TurnIndicatorLightOn_AsSoonAsThereIsFreshCoffee.
Since we have our safety-net of auto-tests, we can do it with disdain.. Piece of cake.

These are the Object cubes (flattened) for the final set of classes. Contrast with the objects in Post 1. So what did I learn?
  • A little DUF helped cut down the number of classes I started off with.. Sketching them out on paper, helped me filter out lazy classes. I think I did JED here.. Just enough design to get moving.. good move.
  • I'm a little sloppy / not thorough with my TDD; I missed out some tests and then went out of my way to add them as and when I remembered. Maybe spending some time to list out all the tests.. just the test-method names as empty stubs could be a counter-measure
  • Felt uneasy for a while while I was building a SensorObserver component (in full) one test at a time without completing any user-stories. Maybe I should have implemented just enough of SensorObserver to implement a story#1..
  • I conveniently forgot about the Brew Button in my initial design sketches.. However it didn't prove to be a big time-sink of a omission.
  • A major chunk of my time was spent debugging a multi-threaded issue. TDD didn't help..Console.WriteLines saved the day. After that it was smooth sailing.
  • Object Cubes aid in thinking about design.. I'm definitely adding this to my toolkit (Although I could do without Side 3.. A simple + (public) and -(private) before the method name helped me depict the public and private contracts)
  • Object Thinking the book shunned "controller" classes. I couldn't think of a way to come up with a CoffeeMaker design that doesn't control the device via the exposed API.
  • This is a very nice OOD problem.. deceivingly simple at first sight..worth burning some brain cells on. Now I need to finish the rest of UncleBob's APPnP book.
Food for thought: I wonder how different the design would emerge if someone just started off and continued one test-at-a-time... without any design up-front?

Want the 69kb source code zip (built onVS2008 Express Edition)?.. drop me a mail at gishu[dot]pillai[at]gmail[dot]com or let me know of an easy way to place this zip on an online shelf.

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