Getting more comfortable with Limelight

April 29, 2009 at 6:45 pm (Graphic Design, Limelight, Ruby, Week 6) (, , , )

OK, Limelight is starting to get fun. I’m finding my bearings in the framework, and I’m learning how to test different types of tasks. It’s really easy to do functional and view testing by adding a macro-style uses_scene :board call in RSpec (it’s built into Limelight as part of its spec_helper.rb). This gives you access to props on the scene that you specify. I’m also seeing some really awesome features of IntelliJ, which I’m learning to use better and am even starting to prefer over TextMate for the refactoring tools: Rename and Extract Method are two of my best friends at this point. Watching over Micah’s shoulder yesterday as he tracked down some Limelight source code, I learned the beautiful Command-Shift-N command to find files by name and autocomplete (like TextMate’s Command-T, which I’d missed very much).

The fact that all of Limelight’s code is in Ruby means there are lots of opportunities to cut down on repetition, which is especially welcome when it comes to Styles and Props (Limelight’s analog of the stylesheets and HTML elements we’d see in Rails). There are some tricks you have to be aware of to share data across files. There’s nothing like Rails’ passing of instance variables from controller to view, as far as I know. But luckily there’s an object called the production that everybody has access to, and we can add attributes to that object to hold data that needs to be available across files (in my case, references to the object that communicates with my Java code and some styling concepts).

And speaking of styling, I’m now armed with a handful of design-oriented links from my designer friends. Most are website gallery sites, but there’s a blog or two in there as well. Now, I’m not under any false impression that I’m suddenly going to be a designer by looking at some websites, but I’m sure I’ll improve. I have two Scenes (like views) in my application, and I’m relatively happy with the styling I did today on the first scene (the game type choices, like “Computer (X) vs. Human (O)”), but the second scene (with the board) definitely needs some work. I got a nice, simple color scheme from, and I even did a little fade animation (you can easily change the transparency of props) as the scene begins.


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Week 5, Friday

April 25, 2009 at 10:22 am (Java, Limelight, Ruby, Week 5) (, , , , , , )

I took the steps necessary to have no parameters in the constructor for my Tic-Tac-Toe view class, so that we could implement the interface in JRuby during our Randori session over lunch. I’d spent a little time thinking about what it would take, so it wasn’t too bad. I had three parameters initially: a Controller, a PlayerFactory, and a Board.

Well, the PlayerFactory was only really being used in one method, and all we really needed there was an array of Strings that showed the types of games that were available, like “Computer (X) vs. Human (O)”. So I changed that method to take an array of strings, and changed uses of that method to pass in information from the PlayerFactory (they were all in the Controller, so no new package dependencies resulted).

Also, since the Controller already had a reference to the same Board object as the View, I just added a getter called getBoard() on the Controller, and used that to set the Board on the View rather than the constructor.

The last thing was taking the controller out of the constructor. The View needs the Controller, for sure, so I added a setter on the View, which any class that instantiates a View would need to call right after creating it. I don’t much like this, since I had to change all my test class setups, and it’s more work for anyone wanting to implement a View, but I think it’s necessary to make the connection to Ruby code.

I also started with the Limelight props and styles being built already, so for the Randori, we focused on implementing the View interface in Ruby. We worked in IntelliJ, and there were a few tongue-in-cheek complaints about that (from Textmate fans). I definitely don’t know IntelliJ as well as I know Textmate or even Vim, but the big plus it has for me is the ease of refactoring, and the color-codification of things that are not going to compile or run properly. At any rate, we got a lot done. After a bit over an hour, with rotation of pairs every 5 minutes, we almost had a running Limelight application that used two computer players. I just had to change a couple lines right afterwards to get it to work as expected.

I have to say, I was initially skeptical when Micah told me we could use my Ruby version OR Java version of Tic-Tac-Toe to implement it in Limelight. I knew my Ruby version worked, but looking back, I knew its OO design was weak; I don’t think there was any kind of display class at all, so I’d have had to change a lot – I may still do that. But to use Java classes in Ruby code? That sounds crazy, but honestly, it wasn’t too bad. But I guess the person showing us how to do this has written a framework using Java and Ruby, so you’ll have to decide for yourself:

require '/Users/colin/IdeaProjects/TicTacToe/tttt.jar'
module Board
def scene_opened(e)
@view = new View(self)

class View
include Java::trptcolin.baseGame.View
# implement methods

Now, it may only be this easy because we’re doing it through Limelight, but either way, I think it’s pretty nifty.

I felt a lot less embarrassed about my abilities during this Randori than at the last one, where I was basically useless. This time I had a lot of domain knowledge to offer (since I wrote the Java code and the Limelight props), but more importantly, I had a better idea of what to test when I was at the keyboard. I still felt slower than everybody else, but at least this time I felt like we were more or less on the same page.

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Week 1, Tuesday

March 24, 2009 at 8:05 pm (Java, Week 1) (, , , , , , )

Okay, so today was harder. I had a flurry of discoveries this morning as I got my questions answered from some work I did last night on the Tic-Tac-Toe game, and then I hit a big roadblock this afternoon. Lesson learned: interrupt when necessary and get questions answered rather than stalling on my own if I’m really stuck.

My problem this afternoon was the Minimax algorithm. I’d looked at it briefly before, after I had finished the Ruby version of the game, but didn’t understand it and gave up. Since the algorithm is part of this assignment, I buckled down and read several descriptions of the algorithm that I found on Google. I thought I understood the mechanics of the algorithm, decision tree and all, but two things were eluding me: the implementation of the decision tree and the computation of the value of a given board position. Eventually I got close (basically translating the pseudocode to Java and Tic-Tac-Toe), but I really did need Micah to help me think through my implementation line by line in order to see a big mistake I was making with recursion. It’s not there yet, but I think it’s close.

Which leads me to the other (maybe bigger) afternoon problem: in my efforts to understand and implement the algorithm, I had neglected TDD and avoided writing tests. Because it was hard => because I’m not good enough at it yet. Well, Micah’s given me some ideas to begin with: sending in board positions where there is a definite best move, and testing that the algorithm spits out the right one, along with some other lower-level things. He did say it’s hard to test, so that makes me feel a little better, but I have to get to the point where I’m not intimidated by TDD. I caught myself jumping ahead to the implementation several times today (and once in front of Micah IN THE TEST CODE – whoops!).

On to the more complete wins of the day, from the morning: I came in with a couple of questions about how to test specific points in the project. Let’s say I have Game, Player, and Board classes. Now, I needed to test that when I told a Player to make a move, the Player would pick a move, and then populate the Board with that move. I was struggling to find a way to verify that the Player had told the Board to populate. It turned out that I just needed a mock Board object. I had an inkling that this is something mocks would be good for, because I remembered a bit of RSpec (ONLY a bit) where an object might have “should_receive(:populate)” to do something similar. I was really glad to come across this problem, because nearly every time I’d read about mocks and stubs in the past I’d come away feeling dumb and defeated. This was simple, though: I just derived a MockBoard class from Board, added a field on the class (private boolean populateCalled = false;), and overrode the populate() method, setting populateCalled = true inside it (and calling super.populate() when I needed the real behavior later).

I’m still incredibly slow in IntelliJ, so I was happy to pick up a few IDEAs about it today. Get it? Get it? I know, I’m incorrigible… Shift-F6 is the Rename refactoring. Wow, is that going to save a lot of time! I think you have to be hovering on the declaration, but the program goes through and changes the name of that method/field/variable/class, in a pretty smart way.

The biggest IntelliJ thing I’m excited to know about is Live Templates, which right now seems exactly like TextMate snippets. Micah wrote me a quick one that does the skeleton of a JUnit test on a tab-complete of “test”, and I can see how this is going to come in handy. I always liked scripting up and using snippets to blast out often-used ERB template things for Rails, and I’m definitely going to start paying more attention to the things that I end up typing over and over so that I can give those to IntelliJ to do.

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