9 Things Every Ruby Newbie Should Know

Transcript

1. 9 @bkeepers things every Ruby Newbie should know
2. Jim Weirich 10 Things Every Java Programmer Should Know About Ruby http://onestepback.org/articles/10things/
3. learn the Ruby way
4. linguistic relativity the structure of a language affects the ways in which its speakers are able to conceptualize their world
5. “A language that doesn’t affect the way you think about programming is not worth knowing.” Alan Perlis
6. don’t just write in Ruby Java
7. don’t just write in Ruby Perl
8. don’t just write in Ruby PHP
9. don’t just write in Ruby C#
10. Learn the Ruby Way
11. follow the conventions
12. ClassName
13. @instance_variable
14. $global_variable
15. SomeConstant ANOTHER_CONSTANT
16. method_name variable_name
17. method?
18. dangerous_method!
19. ClassName file_name.rb
20. Class#method
21. 2 space indent
22. some are enforced
23. some are community standards
24. all values are objects
25. anything that can be bound to a variable
26. no primitives 0.zero? # => true 1.zero? # => false -1.abs # => 1 10.class # => Fixnum (10**100).class # => Bignum true.class # => TrueClass
27. nil is an object a = nil a.nil? # => true a.methods # => list of methods a.class # => NilClass a.abs # => NoMethodError
28. classes are objects a = Array.new
29. almost everything is a message
30. computation… 1. assignment (binding objects to names) 2. primitive control structures (if, else, while) and operators (defined?) 3. sending messages to objects
31. messages are not just function calls
32. function calls use internal lookup tables
33. messages delegate to the object
34. 'hello'.count('l')
35. 'hello'.send(:count, 'l')
36. operators are syntactic sugar 1 + 2 1.+(2) 1.send(:+, 2)
37. array[0] array.send(:[], 0)
38. method_missing class VCR def initialize @messages = [] end def method_missing(method, *args, &block) @messages << [method, args, block] end def play_back_to(obj) @messages.each do |method, args, block| obj.send(method, *args, &block) end end end
39. method_missing require 'vcr' vcr = VCR.new vcr.sub!(/Hello/) { "Goodbye" } vcr.upcase! vcr[8,5] = "Universe" vcr << "!" string = "Hello World" puts string vcr.play_back_to(string) puts string Outputs: Hello World GOODBYE Universe!
40. truthiness
41. nil and false are false
42. everything else is true
43. puts "including zero" if 0
44. Strong dynamic typing
45. weak <?php echo 5 + "5"; ?>
46. strong 5 + "5" TypeError: String can't be coerced into Fixnum
47. 5 + "5".to_i
48. strong dynamic typing
49. static String str = new String("compile"); str = 5; incompatible types found : int required: java.lang.String
50. dynamic a = "runtime" a = [ ]
51. strong dynamic typing
52. duck typing class Duck def talk "quack!" end end class Goose def talk "honk!" end end birds = [Duck.new, Goose.new] birds.each {|b| b.talk }
53. modules
54. namespace module GitHub class User end end user = GitHub::User.new
55. mix-in module Logging def logger @logger ||= Logger.new(opts) end end class Person include Logging def relocate logger.debug "Relocating person..." # do relocation stuff end end
56. Comparable class SizeMatters < Struct.new(:str) include Comparable def <=>(other) str.size <=> other.str.size end end s1 = SizeMatters.new("Z") s2 = SizeMatters.new("YY") s3 = SizeMatters.new("XXX") s1 < s2 #=> true s3.between?(s1, s2) #=> false s2.between?(s1, s3) #=> true [ s3, s1, s2 ].sort #=> [Z, YY, XXX]
57. embrace closures
58. Iteration [1,2,3].each { |item| puts item }
59. Resource Management file_contents = open(file_name) { |f| f.read }
60. Callbacks widget.on_button_press { puts "Got Button Press" }
61. Ruby is loose
62. optional parenthesis puts 'Hello World' puts('Hello World') 'Hello World'.count 'l' puts 'Hello World'.count 'l' puts 'Hello World'.count('l')
63. optional semicolons puts 'Hello World'; don’t use them
64. “constants” Timeout = 30 Timeout = 50 warning: already initialized constant Timeout puts Timeout 50
65. open classes class Integer def even? (self % 2) == 0 end end (1..10).select { |n| n.even? } # => [2, 4, 6, 8, 10]
66. Summary 1. learn the Ruby way 2. follow the conventions 3. all values are objects 4. everything is a message 5. truthiness 6. strong dynamic typing 7. modules 8. embrace enclosures 9. Ruby is loose
67. Thanks! @bkeepers
68. License This presentation is based on “10 Things Every Java Programmer Should Know About Ruby” by Jim Weirich. http://onestepback.org/articles/10things/license.html This presentation is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. http://creativecommons.org/licenses/by-nc/3.0/