A quick introduction to
MacRuby Objective-C, Cocoa, LLVM, Grand Central
and other musings
Olivier Gutknecht - OSDC.fr - Oct. 3 2009

Olivier Gutknecht
olg@no-distance.net
twitter : olg
MacRuby
iCal, iSync, [...] co-founder Active lurker
Server Software

Breaking News !
MacRuby developer
attacked by raptors

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MacRuby

Mac OS X Stack
Applications
Application
Frameworks
Cocoa, WebKit, ...
Core Technologies CoreGraphics, CoreFoundation, ...
Darwin Kernel, userland, libdispatch, ...

Ruby on OS X
2002 Mac OS X 10.2 Ruby 1.6.7
2005 Mac OS X 10.4 Ruby 1.8.2
2007 Mac OS X 10.5 Ruby 1.8.6
RubyCocoa, gems, Rails
2009 Mac OS X 10.6 Ruby 1.8.7
RubyCocoa, gems, Rails
20xx ? Sky is the limit

Ruby on OS X
• Ruby, just on another unix platform
• With some small improvements...
e.g. mongrel_rails_persists on OS X Server
launchd / bonjour integration
• What about Cocoa ?

Family business
SmallTalk
Objective-C Ruby

A “true” OS X App in
Ruby ?
Sure. Check out Gitnub

RubyCocoa
• A ruby-objc bridge
(FUJIMOTO Hisakuni, 2001)
• Ruby 1.8
• Green threads, no reentrance
• Two runtimes, two GC
• ... interesting syntax
• Ouch

require 'osx/cocoa'; include OSX
app = NSApplication.sharedApplication
win = NSWindow.alloc.initWithContentRect_styleMask_backing_defer(
[0, 0, 200, 60], NSTitledWindowMask | NSClosableWindowMask |
NSMiniaturizableWindowMask | NSResizableWindowMask,
NSBackingStoreBuffered, false)
win.title = 'Hello World'
button = NSButton.alloc.initWithFrame(NSZeroRect)
win.contentView.addSubview(button)
button.bezelStyle = NSRoundedBezelStyle
button.title = 'Hello!'
button.sizeToFit
button.frameOrigin = NSMakePoint((win.contentView.frameSize.width/
2.0)-(button.frameSize.width/2.0), (win.contentView.frameSize.height/
2.0)-(button.frameSize.height/2.0))
button_controller = Object.new def button_controller.sayHello(sender)
puts "Hello OSDC!" end
button.target = button_controller
button.action = 'sayHello:'
win.display
win.orderFrontRegardless
app.run

Easy.
(when you’re proficient in Objective-C, Cocoa, Ruby and the bridge - here be dragons)

MacRuby

MacRuby
• One GC to release them all

MacRuby
• One GC to release them all
• One runtime to bind them

MacRuby
• One GC to release them all
• One runtime to bind them
• In the land of Cocoa where Obj-C lie

MacRuby
Laurent Sansonetti
(Apple)
Vincent Isambart
Kich Kilmer
Eloy Duran
Ben Stiglitz
Matt Aimonetti
...
http://www.macruby.org
http://twitter.com/macruby

Modest goals
• The best platform for Ruby developers
• A great platform for Cocoa developers

Bridge, what bridge ?
$ macirb
>> s = "osdc"
=> "osdc"
>> s.class
=> NSMutableString
>> s.class.ancestors
=> [NSMutableString, NSString, Comparable, NSObject, Kernel]
>> s.upcase
=> "OSDC"
>> s.uppercaseString
=> "OSDC"
>> s.respondsToSelector(:upcase)
=> 1
>> s.respond_to?(:upcase)
=> true

Bridge, what bridge ?
• A Ruby class is an Objective-C class
• A Ruby method is an Objective-C method
• A Ruby instance is an Objective-C instance

Syntax
Objective-C
Person *person = [Person new];
[person name];
[person setName:name];
[person setFirstName:first lastName:last];
MacRuby
person = Person.new
person.name
person.name = myName
person.setFirstName(first, lastName:last)

HotCocoa
require ‘hotcocoa’
include HotCocoa
application do
win = window :title => ‘hello OSDC’, :frame => [0, 0, 200, 60]
b = button :title => ‘Hello!’, :layout => {:align => :center}
win << b
b.on_action { puts “Hello OSDC!” }
end
A thin layer by Rich Kilmer, providing a natural
ruby experience when coding Cocoa apps

Ruby 1.9
Parser Runtime Built-in classes
YARV GC Stdlib

MacRuby
Runtime
Parser Stdlib
LLVM/Roxor libobjc Built-in Classes
AOT JIT libauto
CoreFoundation

MacRuby 0.4 - 04/09
• XCode integration
• Embedding / Runtime
Control
• HotCocoa
• Threaded GC

MacRuby 0.5 - xx/09
• YARV ? LLVM !
• RubySpec
• AOT
• GrandCentral
• ...

Why LLVM ?

Coolest Logo Ever

Everybody loves
microbenchmarks
(lies, damn lies and benchmarks)
From a bench by Patrick Thomson @ C4

C
static int fib(int n)
{
if (n < 3) {
return 1;
}
else {
return fib(n - 1) + fib(n - 2);
}
}

Objective-C
@implementation Fib
- (int)fib:(int)n
{
if (n < 3) {
return 1;
}
else {
return [self fib:n - 1] + [self fib:n - 2];
}
}
@end

4
3
execution time (s)
2
1
0
fib(40)
C Objective-C

Ruby
def fib(n)
if n < 3
1
else
fib(n-1) + fib(n-2)
end
end
p fib(ARGV.join("").to_i)

4
3
execution time (s)
2
1
0
fib(40)
C MacRuby Objective-C

MRI Ruby 1.8
$ ruby fibo.rb 40
102334155
MacRuby
$ macruby fibo.rb 40
102334155
MacRuby AOT
$ macrubyc fibo.rb -o fibo
$ ./fibo 40
102334155

Grand Central
# A GCD-based implementation of the sleeping barber problem:
# http://en.wikipedia.org/wiki/Sleeping_barber_problem
# http://www.madebysofa.com/#blog/the_sleeping_barber
waiting_chairs = Dispatch::Queue.new('com.apple.waiting_chairs')
semaphore = Dispatch::Semaphore.new(3)
index = -1
while true
index += 1
success = semaphore.wait(Dispatch::TIME_NOW)
if success != 0
puts "Customer turned away #{index}"
next
end
waiting_chairs.dispatch do
semaphore.signal
puts "Shave and a haircut #{index}"
end
end

Tools Galore
?

Why MacRuby ?
• Ruby for “mac-like” desktop applications
• A wonderful experimentation playground
• ... Interesting perspectives

Q&A
• Ruby 1.9 compatibility
• Right now, ≈ 80% on rubyspec
• Other platforms, portability
• No closed-source dependancies, no
definitive technical blocker
• ... Any takers ?

Thanks!