Dissecting Ruby

Transcript

1. Dissecting a Ruby Block Pat Shaughnessy http://patshaughnessy.net BostonRB Sept. 11, 2012
2. Why learn Ruby internals?
3. 10.times do |n| puts n end
5. Blocks: Closures in Ruby Closures and Metaprogramming
6. rb_block_t ??
7. Calling a block
8. 10.times do str = "The quick brown fox..." puts str end
9. rb_block_t iseq putstring "The quick brown fox… " setdynamic str, 0 putself getdynamic str, 0 send :puts, 1 leave
10. Referencing variables from the parent scope
11. str = "The quick brown fox" 10.times do str2 = "jumps over the lazy dog." puts "#{str} #{str2}" end
12. str = "The quick brown fox"
13. YARV internal stack locals: str rb_control_frame_t LFP
14. str = "The quick brown fox" 10.times do ...
15. YARV internal stack locals: str rb_block_t iseq DFP rb_control_frame_t LFP
16. ... do str2 = "jumps over the lazy dog." puts "#{str} #{str2}" end
17. rb_block_t iseq DFP YARV internal stack locals: str locals: str2 DFP rb_control_frame_t
18. rb_block_t iseq DFP putstring "jumps over the lazy dog." setdynamic str, 0 putself getdynamic str2, 1 tostring putstring " " getdynamic str, 0 tostring concatstrings 3 send :puts, 1, nil, 8, <ic:0> leave YARV internal stack locals: str
20. “In computer science, a closure (also lexical closure or function closure) is a function or reference to a function together with a referencing environment...” Sussman and Steele. Scheme: An interpreter for extended lambda calculus
21. Creating and calling a lambda
23. def display_message str = "The quick brown fox" lambda do str2 = "jumps over the lazy dog" puts "#{str} #{str2}" end end display_message.call
24. def display_message str = "The quick brown fox" ... end
25. YARV internal stack locals: str rb_control_frame_t LFP
26. str = "The quick brown fox" lambda do ... end
27. str rb_control_frame_t LFP rb_env_t env rb_proc_t rb_block_t iseq DFP envval is_lambda Stack Heap str
28. display_message.call
29. locals: str2 DFP rb_control_frame_t rb_env_t env rb_proc_t rb_block_t iseq DFP envval is_lambda Stack Heap str
30. def display_message str = "The quick brown fox" lambda do str2 = "jumps over the lazy dog" puts "#{str} #{str2}" end end display_message.call
31. Blocks: Closures in Ruby Closures and Metaprogramming
32. Using a closure to define a method
33. class Quote def initialize @str = "The quick brown fox..." end def display_message puts @str end end
34. class Quote def initialize @str = "The quick brown fox..." end define_method :display_message do puts @str end end
35. class Quote def initialize @str = "The quick brown fox" end end str2 = "jumps over the lazy dog." Quote.send(:define_method, :display_message) do puts "#{@str} #{str2}" end
36. eval and binding
37. str = "puts" str += " 2" str += " +" str += " 2" eval(str) => 4
38. class Quote def initialize @str = "The quick brown fox..." end def get_binding binding end end
39. obj = Quote.new
40. rb_control_frame_t LFP self RObject ivptr klass @str etc...
41. obj = Quote.new eval('puts @str', obj.get_binding)
42. rb_control_frame_t LFP self rb_binding_t filename line_no env rb_env_t rb_block_t iseq DFP env self Stack Heap RObject ivptr klass @str etc...
43. putstring "The quick brown fox… " setdynamic str, 0 putself getdynamic str, 0 send :puts, 1 leave YARV internal stack locals: str RObject ivptr klass rb_block_t DFP self iseq
44. instance_eval
45. class Quote def initialize @str = "The quick brown fox" end end
46. str2 = "jumps over the lazy dog." obj = Quote.new obj.instance_eval do puts "#{@str} #{str2}" end
47. instance_eval and singleton classes
48. class Quote def initialize @str = "The quick brown fox..." end end
49. obj = Quote.new obj.instance_eval do def display_message puts @str end end
50. obj.display_message The quick brown fox jumps over the lazy dog. Quote.new.display_message ...undefined method `display_message' for #<Quote:0x007fdf789504e8> (NoMethodError)
51. RClass super RClass super Object (class) Kernel (module) Quote (class) RClass super RClass super BasicObject (class) RObject klass obj (object)
52. etc... RClass super RClass super Object (class) obj (object) RObject klass SomeClass (class) RClass super #<Class:#<Quote:0x007f9ed9150c28>> (singleton)
53. http://patshaughnessy.net/ruby-under-a-microscope