Oops! OOP's Not What I Thought

(Presented at Øredev 2018, DomCode 2016)

In this talk we'll go on a historical and philosophical journey deep into the heart of object-oriented programming (OOP). Come along with me as I have my world shaken by the discovery that objects and classes are not the most important concepts in OOP: messages and late binding are. Join me as we try to peek inside the heads of Alan Kay and the other founders of the paradigm as they were developing early object-oriented languages like Smalltalk, only to discover that those "old" ideas seem strikingly relevant today. We may even feel our jaws drop as we realize that OOP and functional programming are not as different as we may have thought, and that the first object-oriented language was not created in the 60's or 70's but much, much earlier…

What awaits us at the end of this journey? At worst, we'll experience a brief crisis of faith in everything we ever thought we knew about programming. (A support group will meet after the conference.) At best, we'll shift the way we view this near-ubiquitous but oft-misunderstood programming paradigm, and walk away with new insights for how we architect and understand our code.

Transcript

1. oops! OOP’s not what I thought @AnjanaVakil Øredev 2018
2. @AnjanaVakil hi, I’m Anjana! - philosophy grad - English language teacher - computational linguist - software developer
3. @AnjanaVakil hi, I’m Anjana! live location data platform for developers mapbox.com
4. @AnjanaVakil hi, I’m Anjana! events.mozilla.org /techspeakers outreachy.org
5. @AnjanaVakil hi, I’m Anjana! The Recurse Center recurse.com
6. @AnjanaVakil hi, I’m Anjana! ...and I had OOP all wrong
7. @AnjanaVakil object- oriented programming objects (!) classes inheritance hierarchy C++, Java
8. @AnjanaVakil object- oriented programming objects (!) classes inheritance hierarchy C++, Java
9. @AnjanaVakil object- oriented programming ?
10. @AnjanaVakil Photo by Marcin Wichary from San Francisco, U.S.A. (Alan Kay and the prototype of Dynabook, pt. 5) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons Alan Kay @AnjanaVakil
11. @AnjanaVakil Alan Kay coiner of “object- oriented” @AnjanaVakil
12. @AnjanaVakil Alan Kay (co-)creator of Smalltalk @AnjanaVakil
13. @AnjanaVakil Alan Kay personal computing pioneer Dynabook @AnjanaVakil
14. @AnjanaVakil Alan Kay undergrad biology major @AnjanaVakil
15. @AnjanaVakil biological metaphors oops #1:
16. @AnjanaVakil what I thought inheritance taxonomy
17. @AnjanaVakil what it is cells organs
18. @AnjanaVakil procedural imperative “Clocks Gears Wallpaper” via Wallpoper (http://wallpoper.com/images/00/38/51/35/clocks-gears_00385135.jpg) @AnjanaVakil
19. @AnjanaVakil object- oriented “Slide of the Week: Increased WBC, April 14, 2011” via Center for Genomic Pathology (http://ctrgenpath.net/wp-content/uploads/2011/04/cml02.jpg) @AnjanaVakil
20. @AnjanaVakil
21. @AnjanaVakil
22. @AnjanaVakil big ideas oops #2:
23. @AnjanaVakil what I thought objects(!) classes
24. @AnjanaVakil Alan Kay “I'm sorry that I long ago coined the term "objects" for this topic because it gets many people to focus on the lesser idea. @AnjanaVakil
25. @AnjanaVakil Alan Kay “The big idea is "messaging"” - To Smalltalk/Squeak mailing list, 1998 wiki.c2.com/?AlanKayOnMessaging @AnjanaVakil
26. @AnjanaVakil what it is messaging late-binding
27. @AnjanaVakil objects @AnjanaVakil
28. @AnjanaVakil messages “Dopamine D3 receptor” via Orientation of Proteins in Membranes Database (http://opm.phar.umich.edu/images/png/3pbl.png) @AnjanaVakil
29. @AnjanaVakil systems Image by The Opte Project (Internet Map) [CC BY 2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons @AnjanaVakil
30. @AnjanaVakil thing.do(some,stuff)
31. @AnjanaVakil to: thing subject: pretty please? :D message: "do", some, stuff
32. @AnjanaVakil recipient message thing.do(some,stuff)
33. @AnjanaVakil recipient message thing.do(some,stuff) method name arguments
34. @AnjanaVakil Ruby thing.do(some,stuff) thing.send(:do,some,stuff)
35. @AnjanaVakil what does do do? how? thing.do(some,stuff) thing.do(other,stuff) child.do(some,stuff) thing.do(some,stuff)
36. @AnjanaVakil early binding @AnjanaVakil
37. @AnjanaVakil late binding @AnjanaVakil
38. @AnjanaVakil beings vs. behaviors oops #3:
39. @AnjanaVakil what I thought objects are nouns
40. @AnjanaVakil what it is objects are verbs
41. @AnjanaVakil data @AnjanaVakil
42. @AnjanaVakil behavior @AnjanaVakil
43. @AnjanaVakil thing.do(stuff) => behavior
44. @AnjanaVakil class Friend: def __init__(self, friends): self.friends = friends def is_friend_of(self, name): return name in self.friends buddy = Friend(['alan', 'alonzo']) buddy.is_friend_of('guy') => False
45. @AnjanaVakil buddy.is_friend_of('guy') buddy.send(:is_friend_of, 'guy')
46. @AnjanaVakil buddy.is_friend_of('guy') buddy.send(:is_friend_of, 'guy') buddy('is_friend_of', 'guy')
47. @AnjanaVakil def Friend(friend_names): my_friends = friend_names def is_my_friend(name): return name in friend_names def responder(method_name, *args): if method_name == 'is_friend_of': return is_my_friend(args) return responder buddy = Friend(['alan', 'alonzo']) buddy('is_friend_of','guy') => False
48. @AnjanaVakil def Friend(friend_names): my_friends = friend_names def is_my_friend(name): return name in friend_names def buddy(method_name, *args): if method_name == 'is_friend_of': return is_my_friend(*args) return responder buddy = Friend(['alan', 'alonzo']) buddy('is_friend_of','guy') => False
49. @AnjanaVakil def Friend(friend_names): my_friends = friend_names def is_my_friend(name): return name in friend_names def buddy(method_name, *args): if method_name == 'is_friend_of': return is_my_friend(*args) return responder buddy = Friend(['alan', 'alonzo']) buddy('is_friend_of','guy') => False
50. @AnjanaVakil def Friend(friend_names): my_friends = friend_names def is_my_friend(name): return name in friend_names def responder(method_name, *args): if method_name == 'is_friend_of': return is_my_friend(*args) return responder buddy = Friend(['alan', 'alonzo']) buddy('is_friend_of','guy') => False
51. @AnjanaVakil boundaries oops #4:
52. @AnjanaVakil what I thought imperative ---------- object-otd ========== functional
53. @AnjanaVakil what it is imperative ========== object-otd ---------- functional
54. @AnjanaVakil Smalltalk class True ifTrue: a ifFalse: b ^ a value class False ifTrue: a ifFalse: b ^ b value
55. @AnjanaVakil Smalltalk class True ifTrue: a ifFalse: b ^ a value class False ifTrue: a ifFalse: b ^ b value Lambda calculus TRUE := λx.λy.x FALSE := λx.λy.y
56. @AnjanaVakil Erlang Fred Hébert Learn You Some Erlang for Great Good learnyousomeerlang.com
57. @AnjanaVakil JS "callbags" André Stalz "Callback Heaven", Amsterdam JSNation 2018 youtu.be/HssczgaY9BM
58. @AnjanaVakil belief structures oops #5:
59. @AnjanaVakil what I thought dogmatic restrictive
60. @AnjanaVakil what it is built for change *or should be
61. @AnjanaVakil simplicity complexity @AnjanaVakil
62. @AnjanaVakil resilience @AnjanaVakil
63. @AnjanaVakil scalability @AnjanaVakil
64. @AnjanaVakil Alan Kay: - The early history of Smalltalk worrydream.com/EarlyHistoryOfSmalltalk - Comment on Moti Ben-Ari's Objects never? Well, hardly ever! computinged.wordpress.com/2010/09/11/moti-asks-objects-never-well-hardly-ever/#div-comment-3766 - E-mail to Stefan Ram on definition of OOP purl.org/stefan_ram/pub/doc_kay_oop_en - E-mail to Squeak list on "messaging" wiki.c2.com/?AlanKayOnMessaging William Cook: - A Proposal for Simplified, Modern Definitions of "Object" and "Object Oriented" wcook.blogspot.com/2012/07/proposal-for-simplified-modern.html - On Understanding Data Abstraction, Revisited cs.utexas.edu/%7Ewcook/Drafts/2009/essay.pdf Anjana Vakil, "Programming across Paradigms" youtu.be/uNPdZm5oF_E Andre Stalz, "Why we need callbags" staltz.com/why-we-need-callbags Structure & Interpretation of Computer Programs mitpress.mit.edu/sicp Learn You Some Erlang for Great Good learnyousomeerlang.com further reading & references
65. David Albert, Darius Bacon, Lindsey Kuper, Julia Evans, Matthew Parker, Ezekiel Smithburg, Juan Hernández, Andy Lee, Michael Arntzenius & the Recurse Center Team Øredev thank you! @AnjanaVakil