Friday, February 23, 2007

The Great Hyderabad Adventure

I have many pictures to share, but they will have to wait for an updated post. Allow your imagination to escort you for now.

So! I had been trapped in the "green zone" at the Novotel Hyderabad for two solid days, and I think I just finally had enough of it. The Novotel is surrounded by about five acres of land, and the edge of that property terminates with a heavy fence (or wall in places) with either barbed wire or razor wire keeping the rabble out...or perhaps keeping the westerners in? I had taken a few strolls on the grounds, and after walking a few hundred meters from one end to the other this morning, I realized I was tired of living in the bubble. It was time to leave.

A number of folks had expressed interest in escorting me into and around Hyderabad, but nothing materialized. Since this was my last chance to see the city, and potentially the last time I'd be in Hyderabad for many years, I had to take matters into my own hands. I asked the front desk for a map, a guidebook, and a few recommendations. Then the transportation desk set up a cab ride to my first destination, Charminar, the square, four-towered heart of the city. It was a perfect if clich├ęd place to start my day of exploration.

Unfortunately, Charminar is also right in the heart of the "old city", the other half of Hyderabad housing the less privileged portion of the population. Charminar itself was certainly astounding. Even though the minarets were closed, the view from the top main floor was quite impressive. In each of the four directions, thoroughfares stretched off into the distance, revealing a bustling mass of humanity. I could see the swarming rickshaws, the teeming bazaar, and the hoards of Hyderabadi citizens going about their lives. It was humbling really. But it was a bit more personal once I descended back into those masses to find my next destination.

India has truly awakened. Here more than anywhere I have visited the contrast between technology and tradition is grossly apparent. Construction projects involve teams of mean working by hand, like ants assembling a colony. But every ant has a cell phone with text messaging and a camera. In the streets, beggars clutch at you constantly, but often speak extremely capable English and understand the western world. Above, signs advertise BizTalk Server and Oracle Training. Below, people sleep in the streets and beg for pennies in roaring traffic. And in the streets of Hyderabad this paradoxical turmoil boils unabated.

So I climbed back down the stairs of Charminar, a bit concerned for my future. Walking out the secured gate, I was immediately mobbed by beggars, young and old. A few (usually the youngest) spoke surprisingly good English. They asked where I was from, what I needed, where I was going. Some (the older members of the hoard) only knew what they needed to elicit a response from western hearts and minds..."food"..."baby"..."hungry"..."please". Why exactly had I decided to launch into this city alone? Ahh, for adventure, I remember. And what happens at this point in an adventure? When the odds and numbers are stacked against you? A gallant escape, with nary a rupee spared. How noble of me.

No, I did not make a contribution to the Hyderabadi poor. I certainly could have. Is it heartless of me? I don't think so; to have made one contribution would have certainly brought a torrent upon me, and it was already a worrisome situation. Instead, I made for a nest of rickshaws near the monument. One particularly bold youth, Abdul, stepped out of the crowd with a map of monuments, a plan for visiting them, and a welcoming smile. He was a salesman with exactly the product I needed, and for the next six hours he would be my guide. Off we went.

One of the previous would-be escorts had suggested Golkonda Fort as a place I should not miss. So naturally, with a friendly and aware guide at my side, that was the next place to visit.

Golkonda is the ruined former home of the Qutub Shahis, before they moved their home to what is now Hyderabad. It is an extensive maze of towers, walls, tunnels, temples, mosques, and overlooks atop a the highest hill in the area. After climbing several hundred feet to the summit, the sprawl of the city extends in all directions. No other view in Hyderabad gives such a complete picture of its size and extent. The fort itself is also impressive, with four-story defensive walls, a remarkable acoustic communication system, and numerous gardens tucked away behind tunnels and through towering arches. The climb to the top required a few breaks, during which Abdul told me what he knew of the fort's history in broken English and snapped photos of me at the major landmarks.

Eventually, we descended, and headed for the next stop on the tour: the Qutub Shahi Tombs.

There were seven Qutub Shahi kings, and they are all interned here in monumental tombs. Each tomb hosts an enormous dome (complete with perfect acoustics for singing, chanting, or tourists clapping and hooting), multiple entrances and side-tunnels, and inside the center, a symbolic (or perhaps more-than-symbolic?) monument to the hosted monarch. Most of the tombs contain a single such monument, but one had three: mother, father, and child. There are tombs here for the seven kings, many of their wives, and other relations. The writing on the monuments is in Arabic. That on the tour signs, in Telugu. Both Hindi and Muslim visit and pay their respects. And the city surrounds. I would say that the Qutub Shahi Tombs are at least as important a stop as the Golkonda Fort. If you are to visit the height of the kings' success, you should at least say an appropriate goodbye.

The rest of my adventure is somewhat less compelling, but perhaps still interesting. Hyderabad as we know it in the western world is really two cities to the Indians: Hyderabad and Secunderabad. In a peculiar quirk of fate, this pair is known to most Indians as "The Twin Cities", just like my home towns of Minneapolis and St Paul are known to Minnesotans (and many Americans) as "The Twin Cities". The very center of Hyderabad, bridging these two cities, is a large lake called Hussein Sagal. Arriving here, I have come full-circle to the heart of the "Twin Cities" on the other side of the world. Unfortunately, the interesting part of that story ends here. Hussein Sagal now appears to be little more than a tourist trap, firmly ensconced in the "new" part of the city. It is surrounded by miraculous science museums and modern family amusement parks. Put simply, I had no interest in anything more than driving past. Yes, it's a large lake in the middle of the city. Yes, there's a 60-foot-tall Buddha standing in the center. The noise of the traffic surrounding and the lights of the shopping malls and Pepsi signs tends to dampen any beauty or majesty that once was there. We moved on.

One item I had expressed interest in when talking to the front desk was "shopping". Unfortunately, we had different definitions of shopping. To me, shopping was visiting a "bazaar of the people", where I could browse sarees for my wife, hand-made toys for my son, and myriad other handicraft and localities. To the hotel, shopping meant "Macy's".

360s, $1 The final stop on my 8-hour Hyderabad tour was, sadly, the LifeStyle department store. It wasn't a bad store, really, since it did host a few local items and the prices were a little better than those at home. But it was a truly western-style store, with little interest to me as anything other than a landing zone. I wandered up to its second story, where I found discounted XBoxVCDs, and a coffee shop so grossly plastered with Windows Vista branding that they even had a "Windows Logo" menu prouding selling "Windows Vista WOWffee". Naturally, I ordered one due to the sheer absurdity of getting a free "Vista Wristlet", a white rubber bracelet emblazoned with the words "Windows Vista. The "Wow" starts here." To make it even more stomach-turning, it was a latte with orange flavoring. Delicious.

Of course I couldn't let the day end with a "WOWffee" and high-quality merchandise at low, low prices, so I called a fellow Sunny from the hotel to join me for a very satisfactory dinner. And then, after consuming excessive amounts of vegetable biriyani, chicken tikka masala, and garlic naan, I returned to the "green zone".

So what have I learned from my excursion?
  1. Exploring the poor districts of an unknown city alone can be frightening, but it certainly gives one perspective on the meaningless nonsense we labor over in the western world.
  2. Don't wait for someone to show you the world; just go see it yourself.
  3. The world is you better see it soon.
I hope I can return to Hyderabad some day to see more of its hidden treasures. For now, I move on to the next JRuby World Tour Stop: BANGALORE.

Wednesday, February 21, 2007

Tech Days Talk a Success

I just completed my talk at Tech Days Hyderabad, and I think it was resounding success. If I heard right, the total head count for my "JRuby Essentials" talk was over 1200 people, by far the largest crowd I've presented for. There was a hoard of questioners immediately after the talk, who followed me into the hall to keep asking. I gave out my entire in-pocket batch of business cards, and even received a round of applause after the JRuby on Rails demo. All this even after my talk was delayed and cut to 40 minutes because the earlier talks ran too long. It was a sprint, but I think it went very well.

I will be posting the slides, but they're basically the same content many of you have probably seen the past couple months. For those who haven't had the pleasure, we'll start posting slides more regularly, and I'll try to blog a few example walkthroughs for those of you who want to duplicate them for your own talks. Feel free to steal it all and spread the word.

Tuesday, February 20, 2007

JRuby World Tour: Hyderabad

Success! It is now 3:00AM in Hyderabad India, and I have checked into the Novotel in HiTec City. The flight was uneventful; I got my demos basically working and then slept the majority of the time. The immigration and customs at the airport were perhaps the least threatening of any I've seen. Immigrations basically just looked for my visa, took my arrival card, and stamped my passport. Customs was little more than a big white X-ray machine with "CUSTOMS" printed on a white piece of paper taped to the front.

The smooth arrival was just what the doctor ordered. The reason I'm on this round-the-globe trip is because my original tickets to India were issued to the wrong name: Charles O'Nutter instead of Charles (O) Nutter. I never noticed the slip-up on the itinerary (nor would I ever have recognized it as a slip-up, since the output was pretty mainframe-ish), and only upon arriving at the airport in Minneapolis was I told I could not check in. Twenty-four hours and a lot of scrambling later, I had new tickets issued on the only flights available, hence my return trip heading east via Bangkok and Tokyo. But aside from that initial snafu, the trip has been pretty routine. Saturday will be ticket to Bangalore has to be purchased in-person, so there's great potential for more headaches. But I can take it in stride, and I'm sure things will work out well in the end.

Hyderabad is about what I expected, and I'm looking forward to getting into the city one of these three days before I leave for Bangalore. It feels very similar to Beijing, with old meeting new and construction everywhere. The city looks very appealing; street-level shops line almost every sidewalk, there's green plant life everywhere, and everything has sort of a dusty, dingy, comfortable feel. It's not dirty, don't get me wrong...just dusty, like any city kicking earth into the air with a thousand construction projects might be. The auto-rickshaws (three-wheeled rickshaw-looking things with small engines) are pervasive; I can imagine that during the day they swarm and buzz like bees. They drive on the British side of the road, which isn't much of a surprise, really.

It's really unfortunate when traveling to more exotic places like this that I have to check into a tidy, pristine western-style hotel. I'd rather stay in the midst of the city, where I can walk out the front door into daily Hyderabadian life. I doubt I'll be at the hotel for all three days of the conference...there's exploring to be done.

If you're located in Hyderabad or Bangalore and might be able to show me around a day this week (Thursday or Friday for Hyderabad) or next Sunday or Tuesday (Bangalore) I'd appreciate it. I'm not put off by crowds of people, even if many don't speak my language, but knowing the hot spots for shopping and eating makes exploring a bit more productive.

I give my presentation in just over 12 hours, so I'm going to try to settle in with a nice Kingfisher lager beer and relax. The conference schedule has things starting up in about 6 hours, so I should be fine for sleep and fairly well-delagged by then.

On the plane, I managed to duplicate the rails-integration WARfile-based deployment of a simple webapp, but I was unable to get an embedded Derby DB to work with it. I'm sure it's a matter of permissions, connection pooling, and such. I may or may not have time to get that working by tomorrow, but if I demo the basic app working with WEBrick and then WAR it up and show the non-DB stuff working in GlassFish, I think the point will have been made. I must also keep reminding myself that my talk is only 50 minutes now. I can fill 50 minutes without batting an eye. So we'll see if there's even time to get to GlassFish, since it eats up a good five minutes building and deploying the app from scratch.

Monday, February 19, 2007

JRuby World Tour: Amsterdam

I'm now relaxing at Schiphol Airport, where I've just plunked down my 10 euros for internet access. After a light breakfast, my current task is now to ensure demos are ready and working for TechDays. I discovered a bit ago that the Rails Integration project uses maven to build, and so I need internet access for that first install command (to pull down required dependencies). I had worried a bit about finding internet access, but this connection appears to be pretty good. I've managed to build the Rails Integration module, and hopefully I'll be able to get Rails-in-a-WARfile working in the next few hours.

If I discover anything interesting in the process, I'll post it. From what I've observed, the rails-integration guys and Ashish have had lots of success lately.

If you happen to be at Schiphol before I depart at 11:55, I'm in Lounge 2 near the brasserie. I'm the one with the MacBook Pro, fighting jetlag and overlooking the concourse.

The next stop will be Hyderabad. My 11:55 flight departs from gate F8.

Update: I managed to get Rails up and running nicely in a WAR file. Huzzah! I'll play with it a bit on the plane and get our usual Rails demo to feed directly into "now we'll make it a WAR file". Thanks much to the rails-integration guys for putting together a really slick piece of work. Gotta love this whole open-source thing.

Side note: jet lag is a weird feeling. Right now it's 9:49 in Amsterdam and around 14:19 in Hyderabad, so I have to pretend it's mid-afternoon. My flight will board in about two hours, and toward the end of the flight I'll have to pretend it's evening and start getting a little sleep. It's quite unfortunate that I'm arriving in Hyderabad at 1:20AM on the day I'm presenting, but that's how it goes!

Sunday, February 18, 2007

The JRuby WORLD TOUR 2007

Yes, you read that right! I'm announcing my intent to circumnavigate the globe in only NINE DAYS spreading JRuby and joy at every stop. The Earth shall be wrapped in JRuby goodness!

To celebrate this monumental occasion, I'm inviting all developers with an interest in Ruby or Java to join the JRuby mailing lists and volunteer your services. Eternal gratitude and temporary fame could be yours, for the small price of bug reports, bug fixes, or high-performance rewrites of core JRuby libraries (it's so easy!). Operators are standing by to receive your emails and direct you to the promised land!

Now, on to the tour!

First Stop: Amsterdam, Netherlands

The first leg of my journey takes me from my home in Minneapolis, Minnesota to beautiful Amsterdam. There I will enjoy an delicious airport breakfast followed by a five-hour tour of the terminal. I will be available for autograph signing from 7:00 to 11:30 by appointment only. The first annual JRuby New-Age Concert of Magic will follow from 11:30 to 11:35. Tickets are first-come, first-served; cash only, please! I will depart from Amsterdam at 11:55 via a chartered jet I'm generously sharing with three-hundred other passengers and a small KLM Dutch Airways flight crew, en route to exotic Hyderabad, India!

Second Stop: Hyderabad, India

The next part of the JRuby "World Domination Tour 2007" takes me to Sun's Tech Days event in Hyderabad. In addition to my JRuby session, Tech Days will host such scintillating topics as "iPod Giveaway" and "Java Jacket Giveaway". But on Wednesday the 21st at 3:35PM you too can learn why JRuby is the programming alchemist's "Developer's Stone", transmuting static lead into dynamic gold. The topics covered will be exactly like those in recent JRuby talks, except cooler, faster, and after 26 hours of non-stop travel and five hours of sleep. Prepare for a punchy, laugh-riotous affair! Will I be able to maintain 90WPM during my interactive demonstrations? Will I remember that "alias" takes two arguments *without* a comma and with the original method first? Join me for what's sure to be 50 minutes you'll remember the rest of your life!

Third Stop: Bangalore, India

From Hyderabad, I take a short one-hour flight to Bangalore, home to Sun Microsystems India and the third leg of the JRuby Globe-trotting Festival of Light! On Monday, February 23rd, I will present JRuby to my tropical counterparts on the opposite side of the earth, featuring the exact same topics from Tech RANDOM ORDER. You never know what I'm going to do next.

I actually have all that Sunday free and Tuesday up until about 8:00 free to do some exploring. Event suggestions are welcome, and I challenge any of you to find food too spicy for me to eat! (impossible, I say!)

Fourth Stop: Bangkok, Thailand

The next step takes me from Bangalore to beautiful Thailand, jewel of Southeast Asia and home to one of my favorite cuisines. I will be available from 4:00AM to 5:30AM for a special, once-of-a-lifetime event I'm calling "JRuby Dawn at Bangkok Airport". And the great question on everyone's lips will be foremost on my mind:

Will the airport's Thai restaurants open before I board my next flight at 6:00? Stay Tuned!

Fifth Stop: Tokyo, Japan

Continuing the Asian leg of the tour, I'll spend 80 fun-filled minutes exploring the international terminal in Narita, only an hour's train ride from the Emperor's Palace! Naturally I'll be available for handshakes and baby-kissing, and hopefully the always-humorous photograph of "buying beer from a vending machine". This trip will serve as a preview for the main Tokyo event: Ruby Kaigi 2007 in June, where I'll finally present JRuby to the Land of the Rising Sun. Come 3:10PM it's time for "so long Japan", but I'll be back soon!

Sixth Stop: Minneapolis, Minnesota

And just 9 days after I departed, I'll be home in Minneapolis again, ready for my next thrilling adventure: The Greater Wisconsin Software Symposium (a No Fluff Just Stuff event) in Milwaukee from March 2-4. Join me for my two fabulous sessions "Bringing Ruby and Rails to the JVM" and "Become Super-Powerful with JRuby", putting the greatest dynamic language ever in the palm of your JVM.

Wednesday, February 14, 2007

Jython 2.2 Beta 1 Released!

The Phoenix Is Rising!

After being considered dead for many years, Jython is back in business with the beta 1 release of Jython 2.2. It's been teetering on the edge of 2.2 compatibility for a long time, but over the past several months the core team and several contributors have rounded off the edges, to the point that a beta release of the long-awaited 2.2 version is now available.

For all you Pythonistas, this should mean two things:

- You have a project for the day. Go get Jython 2.2, try it out with your Python 2.2-compatible apps and libraries, and report any issues you find.
- Start contributing your time, either helping with the Java coding, helping to debug Python apps and libraries, or help on efforts to write C-based libraries in Python.

I will also remind you that a large percentage of JRuby's success is due entirely to its community. Can you really get up in the morning and look at yourself in the mirror without knowing you've helped Jython get back up to speed? Can you?

Tuesday, February 13, 2007

Rails Support Status Update

Things are moving along well I've found time to reimplement String with byte[], work on closures in the compiler, and, well those are posts for another day. Today I update you on the progress of supporting Rails in JRuby.

Rails is quite an interesting beast. I've learned more about Ruby looking through Rails code than from any other source...out of sheer necessity. They say the best way to learn a language is through immersion, right? Is debugging 50-deep stack traces on a questionable interpreter, digging for a reducible test case immersive enough for you? Yeah, I thought so.

We actually hit Rails support hard right at the beginning of this month, or the end of January. The early results were pretty solid, so our efforts have been distracted onto other large JRuby issues not necessarily Rails-related (but all still critical for an eventual 1.0). We also made the bold move of jumping to Rails 1.2.x for all our testing, to show we can keep up with the Rails development process. And to show that we've made great progress, I give you the following results.


ActiveSupport is the base module for Rails. It monkey-patches a number of core classes, provides a multibyte String wrapper for UTF-8 encoded text, and handles most of the details of running and configuring an application. It "supports" the other libraries, and is the first crucial leg needed to run Rails. And so we must "support" it well.

Here's the current results of a full test run:

498 tests, 1809 assertions, 16 failures, 6 errors

That's already in the 95% range, so we're in darn good shape. But it turns out a number of these errors are caused by a glitch in our parser related to KCODE. So if we work around that known issue, the results improve to:

498 tests, 1845 assertions, 12 failures, 1 errors

So more like 97% passing once we fix the KCODE parser problem. The remaining issues are almost all related to time-formatting bugs, with a couple multibyte and exception-handling issues tossed in. I haven't attacked the formatting bugs because Printf code is bloody painful, the multibyte issues are waiting on the KCODE parser fix, and the others...well, they're boring.


ActionPack is the brains of a Rails app, housing the mechanisms for controllers, views, and any code to support them. So it's leg two of the crucial three-legged support necessary to run a Rails application.

I hit ActionPack hard in the past, and a bit this month. Ola took off with it and completed most of the remaining failures. Running with the same KCODE workaround, we have the following results today:

1157 tests, 4811 assertions, 7 failures, 14 errors

That's above 98% passing. The remaining failures include a number of dupes (a single failure that breaks a number of tests), some additional string-formatting failures, and a couple that run ok outside of Rake. So it's damn close to perfect.


You should all know ActiveRecord by now, right? It's Rails' DB layer, based on the ActiveRecord pattern. It is the third core leg of the Rails platform, though you can certainly have apps that don't use AR for database support.

ActiveRecord is an extensive piece of code and it's the only part of Rails that usually requires a native library to run properly (though there is a pure Ruby impl of its MySQL support that nobody uses). In order to support AR, a number of the JRuby community members have cooperated over the past 9 months to build ActiveRecord-JDBC, a gem-installable module that provides ActiveRecord DB support via JDBC. It's a great bit of hackery, and runs surprisingly well considering our less-than-beautiful Java integration performance (under repair).

To limit the scope of this month's Rails work, we're targetting MySQL, since it's the de-facto standard for Rails apps in most quarters. But most of the work we're doing will apply equally well to the other databases, since JDBC is generally very consistent. Tom has been spending lots of time on Derby, for example, to the point that our ActiveRecord-on-Derby failures are almost entirely limited to SQL features it doesn't support yet.

So then ActiveRecord test results, minus the KCODE workaround (since Tom ran these for me):

1012 tests, 3417 assertions, 41 failures, 35 errors

Here our results dip to around 92% passing, but it's really the extended features of AR that have failures here. We've come a long way on this; results on the months-outdated JRuby wiki show Rails 1.1.6's ActiveRecord only passing about 60% of that release's tests, so there's been a ton of improvement since November. And we generally understand how to fix the remaining failures, so it's only a matter of (short) time.


Can you guess what ActionMailer does? ActionMailer provides support for composing, formatting, and sending email from a Rails app. And that's about it. It's not a huge library, but it's essential for many apps.

64 tests, 142 assertions, 9 failures, 6 errors

That's about 75% passing, with a grand total of six test scripts. We haven't focused on this much, other than Tom's initial KCODE work a few months back. The current failures are almost all mail-formatting or SMTP-wrangling issues. I don't expect them to be hard to repair.


Because ActionWebservice's tests require some database setup, we haven't tackled them yet. But I would lay even money that they'll be comparable to ActiveRecord at their worst. For now, they all just fail because MySQL isn't set up correctly for them.

96 tests, 0 assertions, 0 failures, 96 errors

Any community member that wants to dive into ActionWebservice or ActionMailer would fast become a JRuby Hero.


Railties is the final piece of the Rails puzzle, and it...well..."ties Rails" together. I show the results here mostly for completeness; many of the libraries in Railties we'll never support (fcgi, for example) and most JRuby-on-Rails deployments will use alternative mechanisms for hitting the web.

5 tests, 19 assertions, 2 failures, 0 errors

Official Rails Support?

Because things are looking pretty solid, we've been looking for an answer to this question: What does Rails Support in JRuby mean? Do we have to pass all test cases 100% to "officially" support Rails? That might never happen, since there's POSIX and external library stuff we won't ever handle (nor will we need to for JRuby on Rails apps). So then is it a certain percentage? 95%? 98%?

I think the truth is that we could really announce support for Rails now. Almost all the visible, outstanding issues with actually *running* Rails apps have been resolved, and most apps and scripts work fine. There's ongoing work to improve ActiveRecord-JDBC's support for other databases, but that's an endless quest. And of course there's more work needed to support Grizzly, Mongrel, and WAR-based deployment of JRuby on Rails, but those are peripheral to the official announcement. Even when we do make an official announcement, it will be for a pre-1.0 version of JRuby, since we know there's another few months left on 1.0 fixes and features.

So what do you think, dear reader? At what point would you feel safe saying "Let's have our non-JRuby hackers try using JRuby on Rails"? You probably would *be* safe right now, since even if you found issues we've got a busy community ready to help solve them. And we'll probably tiptoe closer to "perfect" Rails support in JRuby over the next couple months, chasing the long tail of Ruby compatibility. But how do these numbers and this update make you feel about JRuby on Rails today?

And as always, we love to have additional contributors, so we'll bend over backwards to make it easy for you to help. Join the lists, join #jruby on freenode IRC, or toss us email privately. JRuby is an amazing community-driven success story, and the only thing missing is you.

California Schemin'

Last week Tim Bray and I were at Menlo Park to meet with the Open Source Software Society Shimane, a delegation of developers, managers, and company heads from the Shimane prefecture of Japan. They were visiting Sun to talk with us about opportunities for cooperation, Sun hardware and software, and most importantly: Ruby. For you see Shimane is the home of Yukihiro "Matz" Matsumoto, creator of Ruby, and he accompanied the group to California.

The evening before the event, we went to Fuki Sushi in Palo Alto, a short two blocks from my hotel. I don't believe I've ever eaten such quantity or variety of Japanese cuisine, and I think our guests felt the same way. They marveled at the size of most dishes, especially the ice-cream-scoop-sized lump of wasabi and the two-foot-long sushi tray. They also photographed almost everything...I think I posed for a couple dozen snaps.

During the following day, Thursday, they sat through numerous presentations on Sun hardware and software. Tim and I also discussed Sun's position on Ruby and JRuby for an hour before and about forty minutes after lunch. Tim hit the high-level points about where Ruby will likely fit into the Java ecosystem in the future, and I supplied details and demos of JRuby. I also threw in a demo of JRuby's compiler beating Ruby 1.8 in the standard fib algorithm, which elicited a smile and laugh from Matz himself (whew! I was worried how he'd react!).

Most interesting to me, however, was my discussion with Matz that night.

I was invited to join the delegation for a crab dinner in San Francisco. We went to Crustacean, a moderately upscale joint near California and 101. And after the attendant tied my plastic bib on, we were ready to go.

Since Matz and I ended up sitting together, and since very few others at the table spoke English, we managed to get in some time discussing a couple Ruby 2.0 design issues. Here's a quick summary:
  • Matz seems to have come around to my visibility proposal for "private" in Ruby 2.0, which is largely the same as how Java handles private visibility. I believe this model is a good simplification over the original proposal. See ruby-core:9996 and related for the original discussion. The basic facts of private then would be:
    • You must dispatch to private methods using a functional call, as in foo() versus I didn't like this at first, but I've come around to using call syntax to force certain aspects of visibility.
    • Dispatches to private methods will only look in the same class for the method definition.
    • Methods that are public in superclasses can't be made private in subclasses.
    • Methods that are private in superclasses are not visible to subclasses, and so new methods of the same name and any visibility can exist in subclasses.
  • Protected methods in Ruby 2.0 could potentially act like private methods now, though Matz is worried it would be too much of a change. I think it's appropriate; current private method behavior is very similar to Java's model for protected methods, where the methods can't be seen from outside the hierarchy, but can be called and overridden within the hierarchy as normal. I voiced my opinion, so we'll see where Matz goes from here.
  • Matz is still comfortable with removing set_trace_func if a better mechanism for profiling and debugging can replace it. I had a few suggestions for alternate mechanisms, but I also promised to look into Java's model, since it seems to work quite well. I also suggested there may be something to learn from DTrace.
  • Matz has come around to the idea that encoded character sequences are a different type than unencoded byte arrays, though he still wants them to have the same outward interface.
This last item warrants a bit more discussion.

The topic of encoded character strings came up a few times during Matz's visit, usually with him asking how we're doing things in JRuby. I explained that we mostly just follow Ruby 1.8, with our String now being backed by a byte[], but that we're also providing out-of-the-box native support for the new Rails ActiveSupport::MultiByte Chars class, a wrapper around string that enforces character boundaries and encodings.

At dinner, we continued the discussion. I made my case for a separate type with the following points:
  • A separate type would not require String's interface to change, and it could remain a byte array
  • By having separate types, we can use polymorphic behavior to avoid checking and re-checking encodings for every operation
The first item was mostly a non-issue...Matz is fairly intent on changing the String interface in 2.0, and much of that work is already complete. But he had an interesting response to the second item: he's already planning to have separate types internally for encoded character strings. This was very good news to me, since it meant that JRuby could easily support M17N in the future by simply providing different String types that handle the other encodings, where our UTF-16 String implementation could simply be backed up by java.lang.String/StringBuffer/Builder.

So the result of the String discussion can be summarized in a few points:
  • String's interface will change from 1.8 to work with characters rather than bytes, both in the encoded and unencoded forms of String. The plan for String methods' behaviors does not change from current Ruby 1.9.
  • String will have subtypes that represent encoded character data, though in most cases you won't need to know about those types. If you do need to go after a UTF8String (my name), you can, but there will also be some sort of factory model for generating encoded strings and Ruby 2's encoding pragma will handle literals.
All told, I think it was a very productive trip, and it was great to help Matz work through a few Ruby 2.0 design questions.