Ruby is Magic - SIGINT Edition

On this years SIGINT (sigint.ccc.de) conference in Cologne, we gave a introduction-level talk on Ruby's principles and concepts, show off some magical code and gave some ideas how to implement your own language (DSL) with Ruby.

Transcript

1. Rb 0.0.21 Eiin
2. Te Piooh o Rb
3. ht://ww. ik.cm/poo/jh_lm/11981/ Tl u, Mt, Wa mks a go pormig lnug? Mt, ivno f Rb 8
4. ht://ic.cnestosewr.og/sos/dti13.hm ★ I hls hmn togt. ★ I hls o tik bte. ★ I mks o a bte porme.
5. ★ “Rb mks pormes hpy.” ★ “I wne o mnmz y futain drn pormig.” ★ “Dn't udrsiae h hmn fco.” ht://ww.atm.cm/it/rb.hm
6. ★ Dsge o porme poutvt n fn ★ Picpe f od sr itrae dsg ★ Picpe f lat atnsmn, mnmz cnuin o eprecd ues Wkpda, ht://e.wkpda.og/wk/Rb_(pormig_lnug)#Piooh
7. Esnil Cnet
8. Eeyhn i a Ojc nil.class # NilClass true.class # TrueClass 42.class # Fixnum
9. (Ams) eeyhn i a Mto 23 - 42 class Fixnum def -(other_fixnum) self + (-1)*other_fixnum end end 8 ti s a mto
10. Fn Fc™ 23.method(:-).class # Method Mtos ae Ojcs 8
11. Oe Cas class Fixnum def days self * (24 * 60 * 60) end def ago Time.now - self end end 10.days # => 864000 2.days.ago # => Wed Jul 03 16:23:42 +0200 2013
12. Coue ae bok o cd, … ★ wih a e asge n pse. ★ wih a e cle ayie y ayn. ★ wih ae acs o vrals d nd n h oiia cnet. ★ I uy l coue rsod o h call() mto
13. Coue array = [1, 'hi', 3.14] array.each do |item| puts item end # => 1 # => 'hi' # => 3.14
14. Dc Tpn ★ Rl es n h sei c ye f n ojc ★ Fcs n h cpblte f n ojc ★ "I t ak ie a dc, t mye s a dc"
15. class RealDatabase def save(object) # Write the object into the database end end class FakeDatabase def save(object) # Do something without a database end end
16. Dnmc Rnie ★ Eeyhn a e cagd drn rnie ★ Itopcin cpblte ★ Nt ctos aot rnie eet
17. 23.respond_to? :days # true class Foo def method_missing(meth, *args) puts "'#{meth}' NOT FOUND" end end Foo.new.bla # 'bla' NOT FOUND
18. Eape o mgcl Rb
19. Dmi Sei c Lnug
20. get "/:name" do "Hello #{params["name"]}!" end
21. class Customer < ActiveRecord::Base has_many :orders, dependent: :destroy validates_presence_of :name end
22. describe Account do it "has a balance of zero when first created" do expect(Account.new.balance).to eq(0) end end
23. Application.configure do client_timeout 2.minutes buffer_size 500.kilobytes end
24. Tcnqe fr bidn DL ★ Cd Bok & Coue ★ Eeuig bok n dffeet cnet ★ …etnig oe suff ★ Mtpormig: dnmc oe gnrto, mto msig clbc
25. Application.configure do client_timeout 2.minutes buffer_size 500.kilobytes end class Application def self.configure(&block) new.instance_eval(&block) end def method_missing(method, *args) @config[method] = args.first end end
26. def method_missing(method, *args) if args.present? @config[method] = args.first else return @config[method] end end
27. ["client_timeout", "buffer_size"].each do |method| define_method method do |value| @config[method] = value end end
28. Dcrtr
29. class DBLayer decorate CacheDecorator def find(id) # … end end
30. class CacheDecorator < BaseDecorator def call(*args) # … before method result = @closure.call(*args) # … after method return result end end
31. Hw?
32. ★ Dtc wih mto sol e dcrtd ★ Etat h dtce mto ★ Iiilz h dcrtr ih ht mto ★ D n a poy mto
33. # Detect the method for decoration def method_added(name) if decorator_class = @decorate_next_with @decorate_next_with = nil DecoratorHelper.apply_decorator(decorator_class, name, self) end end
34. # Extract the original method decorated_method = target.instance_method(method_name) target.send(:remove_method, method_name) # Initialize decorator with original method target.decorators[method_name] = { decorator: decorator.new, method: decorated_method }
35. # Define the proxy method new_method = <<-RUBY def #{method_name}(*params, &block) @_#{method_name}_decorator.call(*params, &block) end RUBY # Add the proxy method to the original class target.class_eval new_method
36. Oe Mr Tig …
38. Kd Wrso a SGN 4 Tmro, satn t 1:0
39. Tak! Dr Bee / @risrs_dr Sbsin Che / @tsa ht://gesamic.d QaA “My Little Pony” © Hasbro Studios and DHX Media Vancouver