How is magic formed

Short excursion into Ruby Internals, Ruby Usergroup Berlin, June 3rd 2014

Transcript

1. How is !
   magic !
   formed
   

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2. Rin!
   @rinpaku @bitcrowd
   

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4. WHY?
   

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5. TIL: There’s bacon in!
   the Ruby source code
   

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6. What happens when Ruby runs my code?!
   !
   What is an Object?
   

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7. What happens !
   when Ruby !
   runs my code?
   

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8. Ruby code
   9.times do
   puts "Ente"
   end
   

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9. Tokens
   9 . t i m e s …
   

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10. 9 . times do puts ""
    Tokens
    9 . t i m e s …
    integer identifier identifier
    period keyword strin
    

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11. Syntax Tree
    do_block
    period
    method_add_block
    integer!
    9
    identifier!
    times
    call
    command
    identifier!
    puts
    …
    

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12. YARV instructions
    “Yet Another Ruby Virtual Machine”
    == catch table
    | catch type: break st: 0002 ed: 0006 sp: 0000 cont: 0006
    |--------------------------------------------------------------
    0000 trace 1
    0002 putobject 9
    0004 send 0006 leave
    == disasm: @== catch table
    | catch type: redo st: 0000 ed: 0009 sp: 0000 cont: 0000
    | catch type: next st: 0000 ed: 0009 sp: 0000 cont: 0009
    |--------------------------------------------------------------
    0000 trace 256
    0002 trace 1
    0004 putself
    0005 putstring "Ente"
    

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13. I MIGHT!
    HAVE MADE
    THIS ALL UP
    

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14. Tokenizing
    Ripper.lex(your_code)
    

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15. parse.c
    

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16. with Ripper:
    Ripper.sexp(your_code)
    !
    Parsing
    

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17. with Ripper:
    Ripper.sexp(your_code)
    parser debug information:
    ruby -y example.rb
    Parsing
    

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18. RubyVM::InstructionSequence.
    compile(code).disasm
    Compiling
    

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19. What !
    is an!
    Object?
    

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20. struct meetup {
    char title[120];
    time_t starts_at;
    bool has_talks;
    };
    Structs
    

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21. union location {
    char address[120];
    struct position {
    int latitude;
    int longitude;
    }
    };
    Union
    

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22. struct meetup {
    char title[120];
    time_t starts_at;
    bool has_talks;
    union {
    char address[120];
    struct position {
    int latitude;
    int longitude;
    }
    }
    };
    

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23. Let’s look at some
    source code
    

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24. RObject
    struct RObject {
    struct RBasic basic;
    …
    };
    

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25. RBasic
    struct RBasic {
    VALUE flags;
    const VALUE klass;
    };
    

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26. RObject
    struct RObject {
    struct RBasic basic;
    struct {
    long numiv;
    VALUE *ivptr;
    struct st_table *iv_index_tbl;
    } heap;
    };
    simplified
    

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27. RObject
    struct RObject {
    struct RBasic basic;
    union {
    struct {
    long numiv;
    VALUE *ivptr;
    struct st_table *iv_index_tbl;
    } heap;
    VALUE ary[ROBJECT_EMBED_LEN_MAX];
    } as;
    };
    

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28. RFloat
    struct RFloat {
    struct RBasic basic;
    double float_value;
    };
    

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29. - Reading C is not that bad.* 

    *(If you hate it, you can still look at the
    Standard Library or Rubinius.)!
    !
    - Check out the Ruby source code

    and give a talk about it. ;)
    Things to take home
    

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30. WAIT! Where’s the bacon?
    

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31. Never create Ruby Strings longer than
    23 characters
    !
    Ruby under a microscope
    (the book)
    !
    The Ruby Hacking Guide
    (Warning: Ruby 1.7.3!)
    !
    A Tour of the Ruby MRI Source Code
    with Pat Shaughnessy
    Some Links
    

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