MacRuby
What is it?
and why should you care?
Presented by: Joshua Ballanco

A bit about me...
• Using Ruby since 2004 (didn’t discover Rails
until 2006)
• Worked for Apple 2006-2010 (Fifth Ave store
& HQ in Cupertino)
• Now at Patch (and just completed a migration
to Ruby 1.9)
• MacRuby Core Team member

A bit about me...
• Using Ruby since 2004 (didn’t discover Rails
until 2006)
• Worked for Apple 2006-2010 (Fifth Ave store
& HQ in Cupertino)
• Now at Patch (and just completed a migration
to Ruby 1.9)
• MacRuby Core Team member
• As of yesterday:
Dr. Joshua Ballanco, Ph.D.

Overview
• Practical MacRuby
• How is MacRuby different?
• Working with Cocoa
• Compiled Ruby!
• Make your millions on the App store
• Nuts & Bolts
• GC
• Regular Expression Engine
• Hash method syntax
• LLVM & other Hacking
• GCD

What is MacRuby?

What is MacRuby?
• http://www.macruby.org
• http://www.macruby.org/files/
• http://www.macruby.org/files/nightlies/
• Available from RVM (but not
recommended)
• Source now located at GitHub!
https://github.com/MacRuby/MacRuby

What is MacRuby?
• Compiling MacRuby:
• Need LLVM (see the README; brew install llvm)
• rake ; sudo rake install
• Bugs – https://www.macruby.org/trac/
report
• MacRuby-devel mailing list
• @macruby, #macruby

No Really, What is
MacRuby?

No Really, What is
MacRuby?
A language with:
• Dynamic typing
• Objects everywhere
• Method calls via sending messages
• Automatic generation of accessors
• Methods can be added to classes at runtime
• Garbage Collection
• Closures

No Really, What is
MacRuby?
A language with:
• Dynamic typing
• Objects everywhere
• Method calls via sending messages
• Automatic generation of accessors
• Methods can be added to classes at runtime
• Garbage Collection
• Closures
...called Objective-C

Ruby Syntax
Parser
MRI’s parse.y
Compiler
RoxorCompiler <C++>
VM (sans GVL)
LLVM (with JIT)
RoxorVM & RoxorCore <C++>
Objective-C Runtime

Integrating with Cocoa
• Bridge Support (please download preview 3
from the “files” page)
• Reads header files and generates XML
descriptions of types and method
signatures
• MacRuby uses BS files to construct calls
and access constants and types

A Ruby You Can
Compile
• macrubyc
• Advantages:
• Faster startup, faster runtime (in most cases)
• Don’t distribute the source!
• Disadvantages:
• ?
• ...some bugs

A Ruby You Can
Compile
• -c → Compile and assemble; good for
multistage builds
• -C → Compile, assemble, and link creating
an *.rbo
• Can also create stand-alone executables
and entire “*.framework”s (experimental)

I wanna be an App
store billionaire...
• Downloads contain Xcode templates
(mostly work in Xcode 4)
• Integration with Interface Builder
• macruby_deploy
• Includes BS files
• Unpacks Gems
• Compiles source

I wanna be an App
store billionaire...

I wanna be an App
store billionaire...
QuickAlarm
Briquette
Timey
Zero2Nine

MacRuby Nuts & Bolts

Garbage Collector:
libauto
• Yet another open source project from
Apple
• The GC for Obj-C
• Based on write barriers
• scanning, conservative, generational, multi-
threaded garbage collector...
• ...unfortunately...slow

Garbage Collector:
the Next Generation(?)
• Ruby does A LOT of allocations
• Nice to not have to stop the world, but...
• Write barriers are slow
• Maybe ref counting?
• Maybe MRI’s collector isn’t so bad after all...

RegExps:
ICU
• Oniguruma is not (real thread) thread safe
• ICU is
• thread safe
• Unicode compatible
• not as crazy feature-full as Oniguruma
• There are some bugs...but honestly, stop
doing that with RegExps!!!

Hash method syntax
• Ruby 1.9’s hash syntax with Symbol keys:
a = { foo: 1, bar: 2, baz: “Hello, world” }
• ...looks a bit like:
[@”Hello, world” rangeOfString:@”Ello” options:
NSCaseInsensitiveSearch]
• Let’s go with that!

Hash method syntax
• MacRuby turns method calls with hash
arguments into SEL
• MacRuby turns method definitions with
hash lists into SEL
• MacRuby can call Objective-C
• Objective-C can call MacRuby, but when
possible you should use:
[[MacRuby sharedRuntime] performRubySelector]

LLVM, JIT, and Hacking
• LLVM provides optimizations
• LLVM provides JIT utilities (kinda slow)
• MacRuby can emit LLVM...
VM_DUMP_IR=1 macruby -e "def foo; puts 'hello'; end;
foo"
• Find other neat tricks in HACKING.rdoc

GCD & The Future

GCD
• MacRuby can tap directly into GCD
• Dispatch module:
• Dispatch::Queue
• Dispatch::Group
• Dispatch::Source
• Dispatch Gem too!

GCD
• Dispatch is a powerful tool for concurrent
programming
• Example: ControlTower
• MacRuby Rack-based server
• Uses GCD to handle requets
• Accomplishes in 1 line what takes Thin/
EventMachine > 6000 lines of C++ &
Ruby

GCD

GCD
• Can we make GCD work in MRI?
• JRuby thinks they can make it work...
https://github.com/headius/jcd
• GCD is Multithreaded Programming, Ruby
Style

Thank you!
http://ofps.oreilly.com/titles/9781449380373/