There's a sound that no presenter wants to hear, and that's dead silence. And that's what greeted me when I made the suggestion in my RubyConf keynote that the community should fork the Ruby language. I think by the end of the talk, though, most people were convinced.
Am I anti Ruby? no.
Am I suggesting Matz is doing a bad job? Not in the least.
But I do think the complexity of the current language inhibits experimentation with language features. Want to implement parallel Ruby? If you do it with the current syntax and semantics, you'll be struggling with the integration of global variables, the non-threadsafe nature of require, continuations, and so on, and so on. So before starting these kinds of experimental projects, I'm saying we should fork the language. Produce variants that let us focus in on the aspects under test. Make the new language a rich-enough subset that you can do useful work with it. Then let people play with it. Maybe the ideas are stellar, in which case we can all talk about integrating the changes back into the mainline language. And maybe the idea didn't pan out, in which case we can quietly forget it, and we've done no damage to the language itself.
A mutation is an altered fork of the original. And mutations are essential to the diversity and strength of a genetic line over time. Let's not be afraid to create Ruby mutants and let them compete.
During our sale, we had one particular request that came in and wedged the application: every time it hit, the mongrel process size zoomed steadily up to 500Mb, so we had to kill it. But finding out which request was doing this was tricky. The log files didn't help—with the amount of traffic we were getting, it was a small needle and a large haystack.
Eventually, we found the culprit. But it would have been a lot easier if I'd thought of this hack on Friday, and not after the sale ended.
If you put this into your application controller:
before_filter :set_process_name_from_request
def set_process_name_from_request
$0 = request.path[0,16]
end
after_filter :unset_process_name_from_request
def unset_process_name_from_request
$0 = request.path[0,15] + "*"
end
then Ruby will set the cmd field in your process control block to the first 16 characters of the request path. You can then use top to see what request is being handled by each mongrel.
Once the request has been handled, an asterisk sign is appended, so you can see the last URL when a mongrel becomes idle.
If your version of top doesn't show the short command by default, use the c keyboard command to see it.
This is probably common knowledge, but I thought it was cool.
The path to a stable Ruby 1.9 has been long. Almost a year ago, 1.9.0 was released. This turned out to have been less than stable. The core library has grown by many hundreds of methods since then. And, probably more significantly, people have started using 1.9 for real, and they've discovered rough edges that needed to be fixed. In particular, the multinationalization support, which is incredibly ambitious, turned out to be hard to use for library writers. James Edward Gray II was probably the first to bump into this as he updated his FasterCSV library (now part of core Ruby) to handle any encoding supported by Ruby. His problems lead to a lot of discussion, and eventually to an entirely new concept inside the interpreter. And as a result, the core team have decided to slip the release of 1.9.1 by at least a month while they investigate other encoding-related issues lurking in the libraries.
In the meantime, a 1.9.1 preview has been released. Details are here.
If you are the maintainer for any publiclyavailable Ruby code (be it a Gem, an application, or whatever) I strongly urge you to download this preview. You'll be doing the community a great service in two ways. First, the various incompatibilities between 1.9 and 1.8 mean that there's a chance that your code may not work without some tweaks. Making those changes now will help others using your code. As importantly, by using 1.9.1 for real, with real code, you'll potentially discover other rough edges. Reporting these back through ruby-core or RedMine will help the Ruby developers further hone the interpreter.
Now, all this delay leaves me with a problem. The new 1.9-specific PickAxe is now content complete. Some people have been waiting for it for 10 months. And I have to decide: should I hold on for the official 1.9.1 release (which will be, at the earliest, at the end of January 2009) or should I send it to the printers? Let me know what you think.
I've reorganized the regular expression content in the new Programming Ruby, and added some cool new advanced examples. This one's fairly straightforward, but I love the fact that I can now start refactoring my more complex patterns, removing duplication.
The stuff below is an extract from the unedited update. It'll appear in the next beta. It follows a discussion of named groups, \k and related stuff.
There’s a trick which allows us to write subroutines inside regular expressions. Recall that we can invoke a named group using \g<name>, and we define the group using (?<name>...). Normally, the definition of the group is itself matched as part of executing the pattern. However, if you add the suffix {0} to the group, it means “zero matches of this group,” so the group is not executed when first encountered.
sentence = %r{
(?<subject> cat | dog | gerbil ){0}
(?<verb> eats | drinks| generates ){0}
(?<object> water | bones | PDFs ){0}
(?<adjective> big | small | smelly ){0}
(?<opt_adj> (\g<adjective>\s)? ){0}
The\s\g<opt_adj>\g<subject>\s\g<verb>\s\g<opt_adj>\g<object>
}x
md = sentence.match("The cat drinks water")
puts "The subject is #{md[:subject]} and the verb is #{md[:verb]}"
md = sentence.match("The big dog eats smelly bones")
puts "The adjective in the second sentence is #{md[:adjective]}"
sentence =~ "The gerbil generates big PDFs"
puts "And the object in the last is #{$~[:object]}"
produces:
The subject is cat and the verb is drinks
The adjective in the second sentence is smelly
And the object in the last is PDFs
We've heard back from Apple. We've double checked with the authors. And the iPhone book is in beta.
After a rocky start, I have to say we've had nothing but help and support from folks in Apple. And eventually the senior management listened to the community and did the right thing. Thanks to our friends in Apple for their help, and thanks to everyone for your support and patience.
Enjoy the book. And write some killer iPhone apps.
A great huzzah! was heard through the land. Apple today announced that they will be lifting the NDA on the iPhone SDK. This is incredibly good news, as it means that, once lifted, developers will be able to talk with each other about the iPhone. And, among those developers are those that have created iPhone content for our Core Animation and iPhone SDK Development Books, a screencast series on iPhone development, and a brand new Pragmatic Studio on iPhone Development. All of these have been sitting here, waiting to get released.
So, all day I've been getting calls and e-mails saying “The NDA is lifted. Where are the books?” The answer is simple: right now the NDA hasn't been lifted. Apple have announced that they will be dropping it, and that a new developer agreement will be sent out within "a week or so." Our developers are still apparently bound by the existing NDA.
So, I spoke with someone senior at Apple this morning, and I'm waiting to hear back. In effect, the NDA is dead. But I need to protect our authors, so we can't release any iPhone content until we hear back that they're out of danger.
I'll blog here when I know more. We'll also send out an e-mail to our announcement mailing list and RSS feed.
I've always wanted to get into Cocoa programming. I like the look and feel of a good Cocoa app, and folks I respect tell me that it's a wonderful environment. But, to be honest, I've always been somewhat put off by the way that Cocoa programming is tightly coupled to Xcode and Interface Builder. I've never really liked IDEs, simply because in the past they've felt like they're in my way.
So then Daniel Steinberg twisted my arm and got me to edit his new book, which introduces Cocoa programming to people who are already programmers in some other OO language. Trying to be a good editor, I gritted my teeth are fired up Xcode and started to follow along with his tutorial chapters. And, somewhat to my surprise, I had a working (if minimal) web browser up and running in a few minutes. I added buttons, and later a progress bar, and it all just worked. So now I've changed my opinion. Cocoa is a really well thought out framework, but the tight integration with Xcode and IB make it very, very sweet. I'm looking for an excuse to spend some serious time writing a decent-sized app with it.
In the meantime, if you're like me, and want to dip a toe into Cocoa development, I'd recommend his Cocoa Programming: A Quick-Start Guide for Developers. If you're more of a hands-on learner, the good news is that Daniel and Bill Dudney will also be running a great 3-day Cocoa Studio at the end of October. It's in the amazing Inverness facility in Denver (which I'm at right now, teaching a Rails Studio with Chad).
Currying is the ability to take a function that accepts n parameters and generate from it one of more functions with some parameter values already filled in. In RUby 1.9, you create a curry-able proc by calling the curry method on it. If you subsequently call this curried proc with fewer parameters than it expects, it will not execute. Instead, it returns a new proc with those parameters already bound.
Let's look at a trivial example. Here's a proc that simply adds two values:
plus = lambda {|a,b| a + b}
puts plus[1,2]
I'm using the [ ] syntax to invoke the proc with arguments, in this case 1 and 2. The code will print 3.
Now let's have some fun.
curried_plus = plus.curry
# create two procs based on plus, but with the first parameter
# already set to a value
plus_two = curried_plus[2]
plus_ten = curried_plus[10]
puts plus_two[3]
puts plus_ten[3]
On line 1, I create a curried version of the plus proc. I then call it twice, but both times I only pass it one parameter. This means it cannot execute the body. Instead, each time it returns a new proc which is like the original, but which has the first parameter preset to either 2 or 10. In the last two lines, I call these two new procs, supplying the missing parameter. This means they can execute normally, and the code outputs 5 and 13.
You can have a lot of fun with currying, but that's not why we're here today.
Over the weekend, Matz added a new method to the Proc class. You can now use Proc#=== as an alias for Proc.call. So, why on earth would you want to do that? Well, remember that === is used to match terms in a case statement. Over of the AimRed blog, they noted that this feature could be used to make the matching in case statements actually execute code. In their example, they manually added the === method to class Proc
class Proc
def ===( *parameters )
self.call( *parameters )
end
end
Then you can write something like
sunday = lambda{ |time| time.wday == 0 }
monday = lambda{ |time| time.wday == 1 }
# and so on...
case Time.now
when sunday
puts "Day of rest"
when monday
puts "work"
# ...
end
See how that works? As Ruby executes the case statement, it looks at each of the parameters of the when clauses in turn. For each, it invokes its === method, passing that method the original case discriminator (Time.now in this example). But with the new === method in class Proc, this will now execute the proc, passing it Time.now as a parameter.
While updating the PickAxe, I noticed that Matz liked this so much that it is now part of 1.9. And it means we can combine this trick with currying to write some fun code:
is_weekday = lambda {|day_of_week, time| time.wday == day_of_week}.curry
sunday = is_weekday[0]
monday = is_weekday[1]
tuesday = is_weekday[2]
wednesday = is_weekday[3]
thursday = is_weekday[4]
friday = is_weekday[5]
saturday = is_weekday[6]
case Time.now
when sunday
puts "Day of rest"
when monday, tuesday, wednesday, thursday, friday
puts "Work"
when saturday
puts "chores"
end
Is this incredibly efficient? Not really :) But it opens up quite an interesting set of possibilities.
Programming is a creative activity. And, like most creative people, programmers occasionally succumb to writer's block. You'll sit there, spinning your wheels, trying random stuff, and knowing that you're not really getting anywhere.
I've been experiencing this feeling now in a different sphere. I've been taking music lessons for some months now, and recently blogged my first composition (or, at least, the first I was prepared to let out into the wild).
Flush with success, I launched into my next piece. I envisaged it being a set of three pieces set in a run-down dance studio. (Don't ask why, it just seemed to fit the mood.) The first section was 5/4 and fairly upbeat. The second section was 3/4, and was deliberately clumsy (I saw partners who couldn't quite get it together), and the last section was 4/4, and knitted things together.
At least that was the vision. I spent weeks on this thing. I had some great themes. But I just couldn't see my way through to the end. Every lesson I'd come in with some changes, and by the end I'd argue myself out of them.
Now I've been coaching developers for a while now. And I know what to suggest when some programmer reaches this kind of state. But for some reason it didn't occur to me to apply the same advice to myself. It took my teacher to say “stop working on this for a while, and go do something fun.” He gave me an assignment. Choose a simple melody and arrange it. Come back with it finished the next week.
In the end, it was great fun. It only took an hour or so, and it totally cleared my mind. I came back triumphantly the next week with something actually finished, and it felt good.
And then, I found I could get back to the more complex piece. In fact, the first time I sat down to it, I was having so much fun I went of in a totally different direction, and I'm now trying something kind of wild. More on that later...
So, if you're finding yourself blocked—if you're going around in circles, or if everything you do you end up throwing away—STOP. Go do something else. Something simple. Something fun. Clear your mind, and remember what it is to enjoy your work.
(And, if you're interested, the fluff piece that cleared my logjam is an arrangement of Shenandoah: transcript and mp3 [played by Mike Springer].)
