For Java programmers is difficult to think in Ruby. For Ruby programmers is difficult to think in Java. In general, switching programming languages is more difficult than most people expect. Here is why.

1. Java is from Mars,
Ruby is from Venus
@nusco
(paolo perrotta)

2. why Ruby

3. expressive

4. fast feedback

5. great community

6. fun

7. why Java

8. powerful tools

9. automated refactoring

10. rock-solid

11. fun

12. learn both

13. difficult

14. - tools__
- values_
- design_

15. tools

16. learning a library

17. the static workflow
1. open the IDE
2. set up a project
3. read the docs
4. write/run code
5. repeat from 3...

18. the dynamic workflow
1. open the interpreter
2. import the library
3. introspect the library
4. try code
5. repeat from 3...

19. the command line

22. functional fixedness
“A mental block against using
an object in a new way that is
required to solve a problem.”

23. the dynamic workflow
1. open the interpreter
2. import the library
3. introspect the library
4. try code
6. repeat from 3...

24. the dynamic workflow
1. open the interpreter
2. import the library
3. introspect the library
4. try code
5. read the source
6. repeat from 3...

25. values

26. “do it right”
vs.
“keep it simple”

30. ethnocentrism
“The viewpoint that one’s own
group is the center of
everything, against which all
other groups are judged.”

31. design

32. bumblebees

34. good design in Java

35. small interfaces

36. many small classes

37. limited inheritance

38. few class methods

39. ActiveRecord

40. require 'active_record'
class User < ActiveRecord::Base
end
user = User.find(:first)
user.name = "Nusco"
user.save

41. require 'active_record'
ActiveRecord::Base.ancestors.count # => 42
ActiveRecord::Base.instance_methods.count # => 240
ActiveRecord::Base.methods.count # => 508

42. require 'active_record'
ActiveRecord::Base.ancestors.count # => 42
ActiveRecord::Base.instance_methods.count # => 240
ActiveRecord::Base.methods.count # => 508

43. modules

44. small interfaces
small classes
limited inheritance
few class methods

45. readability
“once and only once”
decoupling
shared responsibilities

46. the Saphir-Worf hyphotesis
“Our language influences our way
of thinking.”

47. - functional fixedness______
- ethnocentrism_____________
- the Sapir–Whorf hypothesis

48. learning a new language

49. 1. be aware

50. 2. get uncomfortable

51. 3. think generalist

52. 1. be aware__________
2. get uncomfortable_
3. think generalist__

53. thank you.

54. Google: metaprogramming perrotta