This is a set of modified MacRuby presentation slides given at the Pittsburgh Ruby Brigade meeting on Nov 5, 2009. The original presentation was given by Patrick Thomson at C4[3] in September, 2009. Slides 68 and 69 were added by me for the PghRB talk. Patrick's original slides are available at http://www.slideshare.net/importantshock/why-macruby-matters

1. Why MacRuby Matters
Patrick Thomson
C4[3]
September 2009

3. Edsger Dijkstra

4. “Go To Statement Considered Harmful”

5. Dijkstraʼs Algorithm

6. “The effective exploitation of the
powers of abstraction must be
regarded as one of the most vital
activities of a computer
programmer.”

7. Objective-C

8. insufficiently powerful abstraction

9. What does Objective-C lack?

10. 1. code reuse

11. inheritance alone
is not enough

12. singletons

13. inheritance

14. In Objective-C:
1. create a static, shared instance
2. initialize once and only once
3. add an sharedInstance accessor method
…for every singleton class.
Tedious.

15. tedium sucks

16. mixins

17. units of behavior;
mix-in common functionality
across unrelated classes

18. With mixins:
class Example
include Singleton
# your methods here
end

19. foo = Example.instance

20. not a new idea

21. Symbolics Lisp

22. 1980

23. 1. code reuse
2. safety

24. C is powerful.

25. C is powerful. (At the price of safety.)

26. We see Cʼs unsafeness throughout Objective-C.

27. raw pointers: bad news.

28. easily-confusable garbage collection

29. exceptions

30. creation, @try, and @throw are all expensive

31. Cocoa isnʼt exception-safe.

32. mishmash of NSError**,
NSException, and error codes

33. 1. code reuse
2. safety
3. syntactic abstraction

34. [NSArray arrayWithObjects: @"a", @"b", @"c", nil];
vs.
["a", "b", "c"]

35. [NSDictionary dictionaryWithObjectsAndKeys:
@"Chicago", @"location", @"C4", @"event", nil];
vs.
{"location" => "Chicago", "event" => "C4"}

36. [foo compare:bar] == NSComparisonResultAscending
vs.
foo < bar

37. I want a language that lets
Cocoa shine.

38. MacRuby.

39. new Ruby implementation

40. +
powered by LLVM

41. + +
on top of CoreFoundation

42. irb(main):001:0> "c4".class
=> NSMutableString
irb(main):002:0> [1, 2, 3].class
=> NSMutableArray
irb(main):003:0> {:tollfree => "bridging"}.class
=> NSMutableDictionary
irb(main):004:0> "/usr/local/bin".pathComponents
=> ["/", "usr", "local", "bin"]
Ruby objects Cocoa objects

43. irb(main):001:0> 3000.class
=> Fixnum
irb(main):002:0> 3000.is_a? NSNumber
=> true
irb(main):003:0> 3000.is_a? NSObject
=> true
irb(main):003:0> 3000.class.is_a? NSObject
=> true
Everything is an NSObject

45. Laurent Sansonetti
Vincent Isambart
Rich Kilmer
Eloy Duran
Ben Stiglitz
Matt Aimonetti

46. MacRuby isnʼt…

47. a bridge

48. MacRuby != RubyCocoa

49. a toy

50. provides real solutions to
real-world problems

51. example: threading

52. Global Interpreter Locks

53. only one system thread can touch
the interpreter at any given time

54. prevents true multithreading

55. MacRuby has no GIL!

56. So why should you, as Cocoa
developers, use MacRuby?

57. itʼs fast

58. historically slow

59. fib(40)

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

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

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

63. def fib(n)
if n < 3
1
else
fib(n-1) + fib(n-2)
end
end

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

65. Faster than Objective-C‽

66. macruby --compile

67. first ahead-of-time compiler
for Ruby

68. C MacRuby (compiled) Obj-C MacRuby (interpreted)
JRuby Ruby
9
execution time (seconds)
6
3
0
fib(35)

69. C MacRuby (compiled) Obj-C MacRuby (interpreted)
0.3
0.28
execution time (seconds)
0.24
0.2
0.2
0.15
0.1
0
fib(35)

70. itʼs beautiful

71. Objective-C:
[obj setValue:val forKey:key]

72. Bridges:
obj.setValue_forKey(val, key)
READABILITY FAIL

73. no_underscores_plz_k_thx

74. MacRuby:
obj.setValue(val, forKey:key)

75. HotCocoa

76. mapping Cocoa to idiomatic Ruby

77. [[NSImage alloc] initWithContentsOfFile:path];
becomes
image(:file => path)

78. [[NSGradient alloc]
initWithStartingColor: [NSColor greyColor]
endingColor: [NSColor blueColor]];
becomes
gradient(:start => color(:name => "grey"),
:end => color(:name => "blue"))

79. a real, robust macro system

80. itʼs conceptually sound

81. single inheritance
open classes
message-based object model
dynamically typed
garbage-collected

82. Objective-C is C with the Smalltalk
object model attached.
Ruby is Smalltalk with C syntax.

83. itʼs fully integrated with the
Cocoa toolchain

84. Yeah, We Got That

85. itʼs 100% compatible with every
Cocoa framework

86. BridgeSupport lets you call any
C-based API from MacRuby

87. CFStringGetLength("hello C4")
=> 8

88. queue = Dispatch::Queue.concurrent
queue.dispatch do
puts "Asynchronous dispatch FTW!"
end

90. it provides features that
Objective-C lacks

91. regular expressions,
tail-call optimization,
namespaces,
mixins,
operator overloading,
runtime evaluation…

92. What do you lose when going
from Objective-C to MacRuby?

93. static typing

94. JVM : Scala Cocoa : ?

95. Where are we now?

96. almost 0.5

97. SVN trunk is stable
(macruby.org)

98. nightly builds for 10.6 at
macruby.icoretech.org

99. What does the future hold?

100. Last summer I had an internship at Apple.
My views here, however, represent that of an open-source contributor,
and not an Apple employee. Any speculations on the future of MacRuby
are entirely mine and are in no way representative of any plans, attitudes,
or future directions that Apple may take. This presentation is neither
sponsored nor endorsed by Apple.
Apple: please donʼt sue me.

101. performance improvements

102. compatibility

104. not yet

106. Possible? Yes.
Certain? No

107. ahead-of-time compiler

108. MacRuby → x86/ARM machine code

109. full mode: packed with interpreter

110. restricted mode:
no eval(), no interpreter

111. compliant with Appleʼs restrictions
on interpreters in iPhone apps

112. we need garbage collection on
the iPhone

113. Stay Informed
@lrz
@importantshock
@benstiglitz
@MacRuby @vincentisambart
@mattaimonetti
@alloy