1. RubyMotion:
Under the Hood
Inspired by Click and Clack
Monday, October 14, 2013

2. A brief introduction
Monday, October 14, 2013

3. About Me
Name: Joshua Ballanco
Monday, October 14, 2013

4. About Me
Employer: Burnside Digital
Monday, October 14, 2013

5. About Me
Location: Ankara, Turkey
Monday, October 14, 2013

6. A slightly longer
introduction
Monday, October 14, 2013

7. Before...
Monday, October 14, 2013

8. About Me
Employer: Patch
Monday, October 14, 2013

9. About Me
Location: New York City
Monday, October 14, 2013

10. Before that...
Monday, October 14, 2013

11. About Me
Employer: Apple
Monday, October 14, 2013

12. About Me
Location: Cupertino
Monday, October 14, 2013

13. Before that...
Monday, October 14, 2013

14. About Me
School: University of Miami
Monday, October 14, 2013

15. About Me
Location: Miami
Monday, October 14, 2013

16. A bit of history
Monday, October 14, 2013

17. In graduate school
Monday, October 14, 2013

18. In graduate school
Monday, October 14, 2013

19. At Apple... Retail
Monday, October 14, 2013

20. At Apple
Laurent Sansonetti
Monday, October 14, 2013

21. After Apple...
Monday, October 14, 2013

22. Episode VI - The Return
of The RubyMotion
Monday, October 14, 2013

23. What is RubyMotion?
• Use Ruby to build apps for iOS and OS X
• Native apps
• Interface directly with Obj-C libraries
• CLI-based build system
Monday, October 14, 2013

24. What is RubyMotion?
• RubyMotion: http://www.rubymotion.com/
• MotionCasts: http://motioncasts.tv/
• RubyMotion Wrappers:
!
http://rubymotion-wrappers.com/
• ...and lot’s more
Monday, October 14, 2013

25. What is MacRuby?
• Intended to be the implementation of Ruby
2.0 for OS X
• Target RubySpec compliance
• JIT or AOT Compiled
• Uses libauto for Garbage Collection
Monday, October 14, 2013

26. What is MacRuby?
Ruby Syntax
Parser
Compiler
VM (sans GVL)
LLVM (with JIT)
Objective-C Runtime
Monday, October 14, 2013

27. Running a “something.rb” file
Ruby Syntax
Parser
Compiler
VM (sans GVL)
LLVM (with JIT)
Objective-C Runtime
Monday, October 14, 2013

28. Running a “something.rb” file
Ruby Syntax
Parser
Compiler
VM (sans GVL)
LLVM (with JIT)
Objective-C Runtime
Monday, October 14, 2013

29. Running a “something.rb” file
Ruby Syntax
Parser
Compiler
VM (sans GVL)
LLVM (with JIT)
Objective-C Runtime
Monday, October 14, 2013

30. AOT compiling “something.rb”
Ruby Syntax
Parser
Compiler
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
LLVM
something.o

31. AOT compiling “something.rb”
Ruby Syntax
Parser
Compiler
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
LLVM
something.o

32. Running an AOT compiled
“something.rb”
Parser
Compiler
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
something.o

33. Running an AOT compiled
“something.rb”
Parser
Compiler
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
something.o

34. Running an AOT compiled
“something.rb”
Parser
Compiler
LLVM
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
something.o

35. Running an AOT compiled
“something.rb”
Parser
Compiler
LLVM
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
something.o

36. Running an AOT compiled
“something.rb”
Parser
Compiler
LLVM
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
something.o

37. What is RubyMotion?
• Descendent of MacRuby
• “Ruby, the Good Parts”
• Static Compiled
• Retain/release reference counting
Monday, October 14, 2013

38. Static compiling “something.rb”
Ruby Syntax
Parser
Compiler
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
LLVM
something.o

39. Static compiling “something.rb”
Ruby Syntax
Parser
Compiler
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
LLVM
something.o

40. Running a static compiled
“something.rb”
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
something.o

41. Running a static compiled
“something.rb”
VM (sans GVL)
Objective-C Runtime
Monday, October 14, 2013
something.o

42. Why must we statically
compile?
• On OS X
• Compile writes code to a memory
page
• Runtime runs the code from that
memory page
Monday, October 14, 2013

43. Why must we statically
compile?
•
On iOS
Memory pages must be writable or
executable, NOT BOTH!
•
•
•
Monday, October 14, 2013
•
OS prohibits runtime compilation
Apple prohibits interpreting arbitrary scripts
...but you wouldn’t want an interpreter
anyway

44. Garbage Collection
Monday, October 14, 2013

45. What happened to the
Garbage Collector?
It required extra threads, so we
had to kill it...
Monday, October 14, 2013

46. So RubyMotion Uses
ARC?
Yes...
Uh...no
...sorta?
Monday, October 14, 2013

47. ARC vs “ARC”
• Objective-C’s ARC modifies your code
before compilation
• RubyMotion VM knows when retain and/or
release should be called...your code is not
touched
Monday, October 14, 2013

48. ARC vs “ARC”
Isn’t the distinction
rather academic?
Probably...
Monday, October 14, 2013

49. “ARC” Caveats
• Collection happens when the autorelease
pool drains
• Need to be careful with tight loops that
generate many objects
• Use “autorelease do...end”
• Detects almost all cycles
• Use WeakRefs if cycles become
problematic
Monday, October 14, 2013

50. Debugging RubyMotion
• Remember, RubyMotion objects are
Objective-C objects...
• All the usual tricks are valid!
Monday, October 14, 2013

51. Let’s Play!
Monday, October 14, 2013

52. The Victim
app/app_delegate.rb
Monday, October 14, 2013

53. The Victim
app/app_delegate.rb
Monday, October 14, 2013

54. REPL Magic
Monday, October 14, 2013

55. REPL Magic
Monday, October 14, 2013

56. REPL Magic
Monday, October 14, 2013

57. REPL Magic
Monday, October 14, 2013

58. That’s cool...but can
you do it in a
debugger???
Monday, October 14, 2013

59. Debugger Wizardry
Monday, October 14, 2013

60. Debugger Wizardry
Monday, October 14, 2013

61. Debugger Wizardry
Monday, October 14, 2013

62. Debugger Wizardry
Monday, October 14, 2013

63. That’s CRAZY!
I know...but it’s fun!
Monday, October 14, 2013

64. Debugging RubyMotion
• Helper methods “pro” and “pri”
• http://www.rubymotion.com/developercenter/articles/debugging/
• Watch for more/better tooling to come...
Monday, October 14, 2013

65. Questions?
Joshua Ballanco
@manhattanmetric
https://github.com/jballanc
Monday, October 14, 2013