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µObjects: Temporally Coupled Decisions into Chain of Responsibility

µObjects: By Example - Playing Cards

I've been a bit remiss on good code examples for µObjects. I've been planning a few things; never got them done. Almost entirely because I'm lazy. So...

I'm going to try a simple example of the application of µObjects.

Playing cards. I was gonna do Magic: The Gathering (M:TG) cards; but they're a bit complex for an initial go. And not sure everyone will be as familiar witih M:TG. A co-worker is trying to get a better understanding of the µObject idea using M:TG cards as a base. It's one I'd like ot tackle. It presents a lot of places to implement things multiple ways; showing one of the strengths of µObjects; You can cleanly do things a number of ways. Though... please pick just one for your code base. :)

I'm going to code this up and write it up at the same time as I have a lot of other coding posts. This will make it a bit more "real time" and I can demonstrate the process much better.

My goal is scoring a single hand of poker. I've done a black jack scoring engine before; but I want to throw a little more umph into the final product of this.

Scoring a 5 card Poker Hands Ranked from Highest to Lowest:

  • Royal Flush
    • A straight from a ten to an ace with all five cards of the same suit. In poker all suits are ranked equally.
  • Straight Flush
    • Any straight with all five cards of the same suit.
  • Four of a Kind
    • Any four cards of the same rank. If two players share the same Four of a Kind (on the board), the bigger fifth card (the "kicker") decides who wins the pot.
  • Full House
    • Any three cards of the same rank together with any two cards of the same rank. Our example shows "Aces full of Kings" and it is a bigger full house than "Kings full of Aces."
  • Flush
    • Any five cards of the same suit (not consecutive). The highest card of the five determines the rank of the flush. Our example shows an Ace-high flush, which is the highest possible.
  • Straight
    • Any five consecutive cards of different suits. Aces can count as either a high or a low card. Our example shows a five-high straight, which is the lowest possible straight.
  • Three of a Kind
    • Any three cards of the same rank. Our example shows three-of-a-kind Aces, with a King and a Queen as side cards - the best possible three of a kind.
  • Two Pair
    • Any two cards of the same rank together with another two cards of the same rank. Our example shows the best possible two-pair, Aces and Kings. The highest pair of the two determines the rank of the two-pair.
  • One Pair
    • Any two cards of the same rank. Our example shows the best possible one-pair hand.
  • High Card
    • Any hand not in the above-mentioned hands. Our example shows the best possible high-card hand.

While traditional Poker doesn't rank suits, I think it adds a bit of complexity to the problem; so the suits will be ranked: Spades > Heart > Diamonds > Clubs.

That's my main feature. Compare hands. The simplest of these hands is High Card. Which is a card comparrison. I'll start with implementing just a card comparrison.
That's a pretty good initial objective.

I don't expect to get all the way to scoring hands; but being able to compare two cards is some solid value add to what I'm working towards.

Initial Recording Finished

I didn't get around to typing while recording. I talked a lot though; aren't you lucky.

What I've done in this first recording is using TDD to create the Card Comparison pieces. It's not a huge amount. I spent about 4 hours going through and getting it to this point. Probably could have gone faster if I shifted a few things. I had a few wrong paths that took some time.

Mistakes are there to learn from. I actually found a problem when applying a pattern in certain situations. The Decorator patter isn't the simple solution when you'll need to compare values that can be decorating. Slight spolier - The Suit is not a good decorator.

I don't want to get this up until I have the video edited. I'd really like to wait until I have it all the way through scoring; then just list the video's as resources.

I'll see where this gets to.

Video Edited

I've gotten the video edited and uploaded to YouTube.
I haven't gotten a transcript. I did all the coding and talking while coding on the fly.
I've sped up the beginning and end of the video quite a bit. It's not terribly interesting parts.

The core of the video is breaking down a temporally coupled procedural method into µObjects.

My original dialog is largely left in, minus some editing; like the phonecall I forgot to hit "stop" for... oops.

This video; while I didn't really have plans for what it would be; is an example of Temporally Coupled Decision Making into Chain of Responsibility.

A lot like Woody Zuill says, "You'll find the work that needs doing by doing the work." In this case, I found the purpose of the video by making the video. :)

Video Editing ... for phun

I've found video editing isn't really my thing. I used Adobe Premiere; I tried a few... and it's the one that seemed to work the best for me. A couple others I tried used about 4x the memory. The video was 4 hours total; and a few of the tools didn't do so well with that.
Premiere only hiccuped a couple times. I suspect I'll do month-to-month subscription to complete this video project. By which I mean I'll pay for a month to do a few days of editing. Cancel... and repeat each time I do a video. :)
I don't hate it as much as I did just starting the editing. I think this will be some good practice for me on how to present information; especially in a video format.


THe code is available in my MicroPlayingCards repo with the final commit of this video being here.

Quinn Gil

Quinn Gil

Seattle Code Crafter. Quinn beats the drum of FAST Agile, Extreme Programming and Object Oriented Design through MicroObjects. He blogs for fun and frustration of exploring new concepts.

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µObjects: Temporally Coupled Decisions into Chain of Responsibility
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