This document provides an overview of MacRuby, which is a Ruby implementation that runs on Apple's Cocoa and Objective-C frameworks. It summarizes that MacRuby allows Ruby code to be compiled to machine code using LLVM, integrated with Cocoa for building macOS apps, and leverages Grand Central Dispatch (GCD) for concurrency. The presenter is a MacRuby core team member who has been using Ruby since 2004 and worked at Apple from 2006-2010.

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

2. 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

3. 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.

4. 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

5. What is MacRuby?

6. 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

7. 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

8. No Really, What is
MacRuby?

9. 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

10. 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

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

12. 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

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

14. 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)

15. 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

16. I wanna be an App
store billionaire...

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

18. MacRuby Nuts & Bolts

19. 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

20. 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...

21. 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!!!

22. 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!

23. 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]

24. 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

25. GCD & The Future

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

27. 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

28. GCD

29. 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

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