Re: Power Assert in Ruby

http://regional.rubykaigi.org/oedo05/

Transcript

1. RE: POWER ASSERT
   IN RUBY
   Kazuki Tsujimoto
   

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2. ࣗݾ঺հ
   • “VM Bug Hunter”
   • ॳAsakusa.rb
   

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3. • Ξαʔγϣϯϝιου/Ϛονϟͷ࢖͍෼͚ʹ೰·ͣʹ
   ςετΛॻ͚ΔΑ͏ʹ͢ΔͨΊpower_assertΛ࡞ͬͨ
   • assert {expr}͚͍֮ͩ͑ͯΕ͹Α͍
   • 1==3ͷ໭Γ஋͕දࣔ͞Ε͍ͯͳ͍ͱ͍͏໰୊͕͋Δ
   $ ruby test_example.rb
   assert { [0, 1, 2].find {|i| i.odd? } == 3 }
   |
   1
   POWER ASSERT IN RUBY
   

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4. • ࣮૷ʹ࢖͍ͬͯΔTracePointͷ੍໿
   • ϝιουݺͼग़͠ͷ࠷దԽʹΑͬͯɺΠϕϯτ͕ىಈ
   ͞Εͳ͘ͳ͍ͬͯΔ
   • ࣄલʹpower_assertΛrequireͯ͠࠷దԽΛແޮԽ͢Ε
   ͹Α͍͕ɺ͜Ε͸खؒ
   $ ruby -rpoewr_assert test_example.rb
   assert { [0, 1, 2].find {|i| i.odd? } == 3 }
   | |
   | false
   1
   POWER ASSERT IN RUBY
   

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5. • akr͞Μ͔Β࠷దԽର৅ͱͳΔϝιουΛʮ͜
   ͱ͝ͱ͘࠶ఆٛͯ͠ݩʹ໭ͯ͠͠·ʯ͑͹Α
   ͍ͷͰ͸ͳ͍͔ͱͷࢦఠ
   • ࣄલrequireΛෆཁʹ͢Δ͜ͱ͸Ͱ͖Δͷ͔
   POWER ASSERT IN RUBY
   

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6. ໰୊
   • 1 == 3ͷ==ϝιουݺͼग़͠ͷΠϕϯτ͕र
   ͑ͳ͍
   trace = TracePoint.new(:return, :c_return) {|tp|
   p tp.method_id
   }
   trace.enable {
   1 == 3
   }
   

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7. ݪҼ
   • Fixnum#==ͳͲͷجຊతͳϝιου͸ಛघ
   έʔεѻ͍Ͱ؆ུԽͨ͠ॲཧΛ͍ͯ͠ΔͨΊ
   if (FIXNUM_2_P(recv, obj) &&
   BASIC_OP_UNREDEFINED_P(BOP_EQ, FIXNUM_REDEFINED_OP_FLAG)) {
   return (recv == obj) ? Qtrue : Qfalse;
   }
   else if(...) {
   ...
   }
   ...
   CALL_SIMPLE_METHOD(recv);
   ಛघέʔε(1)
   ಛघέʔε(..N)
   Ұൠέʔεɹ
   

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8. ରࡦ
   • ૉ௚ͳΞϓϩʔν(࠶ఆٛͰϑϥάΛཱͯΔ)
   • Fixnum.method_addedΛϢʔβ͕ఆٛͯ͠
   ͍Δ৔߹ͳͲʹӨڹ͕ग़Δ
   class Fixnum
   alias eq_orig ==
   def ==(other)
   eq_orig(other)
   end
   alias == eq_orig
   end
   

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9. ରࡦ
   • ࠾༻ͨ͠Ξϓϩʔν(࠶ఆٛҎ֎ͰϑϥάΛཱͯΔ)
   • ՄࢹੑΛ໌ࣔతʹઃఆ͢Δ(Ruby 2.0ʙ2.2)
   • refine͢Δ(Ruby 2.0ʙ2.3dev)
   class Fixnum
   public :==
   end
   module M
   refine Fixnum do
   def ==; end
   end
   end
   

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10. ଓɾ໰୊
    • C.new == C.newͷ==ϝιουݺͼग़͠ͷΠ
    ϕϯτ͕र͑ͳ͍
    trace = TracePoint.new(:return, :c_return) {|tp|
    p tp.method_id
    }
    class C; end
    trace.enable {
    C.new == C.new
    }
    

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11. ଓɾݪҼ
    • ϝιουͷ࣮ମ͕ಛఆͷCؔ਺(rb_obj_equal)
    ͩͬͨͱ͖͸ಛघέʔεѻ͍Ͱ؆ུԽͨ͠ॲ
    ཧΛ͍ͯ͠ΔͨΊ
    ...
    vm_search_method(ci, cc, recv);
    if (check_cfunc(cc->me, rb_obj_equal)) {
    return recv == obj ? Qtrue : Qfalse;
    }
    ...
    CALL_SIMPLE_METHOD(recv);
    

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12. ଓɾରࡦ
    • ૉ௚ͳΞϓϩʔν
    • ϝιουΛ࠶ఆٛͯ͠ݩʹ໭͞ͳ͍
    • BasicObject.method_added(ུ)
    • ϞϯΩʔύον͕ద༻͞Εͨঢ়ଶͰϢʔβίʔυ͕࣮ߦ͞
    Εͯ͠·͏
    class BasicObject
    alias eq_orig ==
    def ==(other); eq_orig(other); end
    alias == eq_orig
    end
    

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13. ଓɾରࡦ
    • ࠾༻ͨ͠Ξϓϩʔν
    • refine͢Δ(refine͞Ε͍ͯΔ͜ͱΛࣔ͢ಛघͳϝιου
    ΤϯτϦΛrb_obj_equalͷલʹૠೖ͢Δ)
    • ͲͪΒͷΞϓϩʔνͰ΋Rubyͷඪ४Ϋϥεʹ͍ͭͯ͸ࣄલʹ
    ରԠ͓ͯ͘͜͠ͱ͕Մೳ͕ͩɺC֦ுͰ࡞੒ͨ͠Ϣʔβఆٛ
    Ϋϥε·Ͱ͸ٹ͑ͳ͍ͱ͍͏՝୊͸࢒Δ
    module M
    refine BasicObject do
    def ==; end
    end
    end
    

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14. ଓʑɾ໰୊
    • C.new == C.newͷ==ϝιουݺͼग़͠ͷΠ
    ϕϯτ͕1ճ͔͠र͑ͳ͍
    trace = TracePoint.new(:return, :c_return) {|tp|
    p tp.method_id
    }
    class C; end
    trace.enable {
    loop {
    C.new == C.new
    }
    }
    

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15. ଓʑɾݪҼ
    • 1ճ໨ͷݺͼग़࣌͠ʹʮ࠷ऴతʹrb_obj_equalΛݺͿʯ
    ͱ͍͏৘ใΛΠϯϥΠϯΩϟογϡʹ࣋ͬͯ͠·͏ͨΊ
    Lightweight Method Dispatch on MRI(Koichi Sasada)͔ΒҾ༻
    

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16. ଓʑɾରࡦ
    • దٓΩϟογϡΛΫϦΞ͢Ε͹Α͍
    • power_assertͰ͸assertʹ౉͞ΕͨϒϩοΫΛݺ
    ͼग़͢λΠϛϯάͰΫϦΞ
    • ΩϟογϡͷΫϦΞʹ΋RefinementsΛར༻
    • ۭϞδϡʔϧΛusing
    

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17. ·ͱΊ
    • power_assertͷࣄલrequire͸΄΅ෆཁʹ
    • ׬શͰ͸ͳ͍͕௨ৗͷϢʔεέʔε͸Χόʔ
    • Rubyͷ಺෦࣮૷ʹڧ͘ґଘ͓ͯ͠Γࠓޙ΋ಈ࡞
    ͢Δ͔͸ෆಁ໌
    • Ҿ͖ଓ͖ࣄલrequireΛਪ঑
    

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