How is magic formed

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

Transcript

1. How is ! magic ! formed
2. Rin! @rinpaku @bitcrowd
4. WHY?
5. TIL: There’s bacon in! the Ruby source code
6. What happens when Ruby runs my code?! ! What is an Object?
7. What happens ! when Ruby ! runs my code?
8. Ruby code 9.times do puts "Ente" end
9. Tokens 9 . t i m e s …
10. 9 . times do puts "" Tokens 9 . t i m e s … integer identifier identifier period keyword strin
11. Syntax Tree do_block period method_add_block integer! 9 identifier! times call command identifier! puts …
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 <callinfo!mid:times, argc:0, block:block 0006 leave == disasm: <RubyVM::InstructionSequence:block in <compiled>@<co == 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"
13. I MIGHT! HAVE MADE THIS ALL UP
14. Tokenizing Ripper.lex(your_code)
15. parse.c
16. with Ripper: Ripper.sexp(your_code) ! Parsing
17. with Ripper: Ripper.sexp(your_code) parser debug information: ruby -y example.rb Parsing
18. RubyVM::InstructionSequence. compile(code).disasm Compiling
19. What ! is an! Object?
20. struct meetup { char title[120]; time_t starts_at; bool has_talks; }; Structs
21. union location { char address[120]; struct position { int latitude; int longitude; } }; Union
22. struct meetup { char title[120]; time_t starts_at; bool has_talks; union { char address[120]; struct position { int latitude; int longitude; } } };
23. Let’s look at some source code
24. RObject struct RObject { struct RBasic basic; … };
25. RBasic struct RBasic { VALUE flags; const VALUE klass; };
26. RObject struct RObject { struct RBasic basic; struct { long numiv; VALUE *ivptr; struct st_table *iv_index_tbl; } heap; }; simplified
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; };
28. RFloat struct RFloat { struct RBasic basic; double float_value; };
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
30. WAIT! Where’s the bacon?
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