The Timeless Way of Building

"Design patterns" is a common phrase that is often spoken in the course of design and development of web applications. But it's genesis is not from programming, but Architecture. They come from a trio of books in the 1970s by Christopher Alexander, the most famous of which is the middle book: "A Pattern Language". The issue arises that Pattern Languages, much like spoken languages, are most effective when the speaker is fluent. We'll look at the origin of pattern languages and why they can be dangerous and even detrimental tools in the hands of the inexperienced designer and developer through examples of bad grammar and poor idiomatic choices (aka antipatterns), and perhaps some architecture as well.

Transcript

1. BUILDING THE TIMELESS WAY OF John Athayde RUBYNATION MAY 2013
2. I’m Jean Valjean. WHO AM I?
11. Get our bearings here... WHAT WE’RE GONNA COVER
12. PATTERNS ARCHITECTURE PATTERN LANGUAGES & HISTORY ANTI-PATTERNS APPLY some THEORY
13. LET’S GET ON THE SAME PAGE “PATTERNS”
15. A design pattern systematically names, motivates, and explains a general design that addresses a recurring design problem in object-oriented systems. It describes the problem, the solution, when to apply the solution, and its consequences. It also gives implementation hints and examples. The solution is a general arrangement of objects and classes that solve the problem. The solution is customized and implemented to solve the problem in a particular context.
16. 1 3 2 4 DESIGN PATTERNS
17. 1PATTERN NAME
18. 2 The Problem
19. 3The solution
20. 4consequences
21. “Design patterns help you identify less-obvious abstractions and the objects than can capture them. For example, objects that represent a process or algorithm don’t occur in nature, yet they are a crucial part of flexible designs.”
22. Iterator Pattern Iterate over elements of a collection without exposing the internals...
23. .each
24. Patterns?
28. The Three-book series
29. “How can you distribute responsibility for design through all levels of a large hierarchy, while still maintaining consistency and harmony of overall design?” — M. J. Dominus 2002 ALEXANDER’S QUEST:
32. PRINCIPLES ARE PATTERNS
33. DRY
34. YAGNI
35. SRP SINGLE RESPONSIBILITY PRINCIPLE
36. OCP OPEN/CLOSED PRINCIPLE
37. LSP LISKOV SUBSTITUTION PRINCIPLE
38. ISP INTERFACE SEGREGATION PRINCIPLE
39. DIP Dependency inversion PRINCIPLE
40. S O L I D SRP OCP LSP ISP DIP
41. WHERE DID PATTERNS COME FROM? ARCHITECTURE
55. WORKING WITHIN THE LANGUAGE OF CLASSICAL ARCHITECTURE.
60. http://www.flickr.com/photos/cindy47452/3682879190/
61. crafstmen
62. ENGINEERS
63. architects
64. BUILDERS W E F A N C Y O U R S E L V E S
65. “Engineers frequently have to make decisions of great practical consequence in the face of incomplete and uncertain knowledge.” — Walter Vincenti ON ENGINEERS:
66. PROBLEM: too many people think that “design patterns” in software means a library of Code templates.
67. http://www.patterntap.com
68. “ design patterns are suggested approaches seen in the wild. - B R I A N H O G A N ”
69. STRIVING SO WHAT ARE WE TOWARDS?
70. HAS NO NAME THE QUALITY OF A SPACE that
71. Gibellina, Italy
72. Gibellina Nuova, Italy
73. Welcome to negative town. ANTIPATTERNS
74. D
76. Gibellina Nuova, Italy D
77. “Big Ball of Mud” Paper (aka Shanty Towns) D
78. D
79. Walking the Tree D
80. Inheritance Everywhere D
81. 2 COMPOSITION DELEGATE
82. @account.customer.address.state D
83. class Customer < ActiveRecord::Base has_one :address has_one :account ... def state address.state end ... end @account.customer_state 2
84. FAT Models D
85. MODULES CONCERNS PLUGINS* GEMS ENGINES 2
86. CALLBACKS before_validation before_validation on: :create after_validation after_validation on: :create before_save before_create after_create after_save 2 D
87. RAILS IS A SERIES OF VERY LARGE TUBES LIBRARIES 2 D
88. class RemoteProcess < ActiveRecord::Base scope :running, where(:state => ‘Running’) scope :system, where(:owner => [‘root’, ‘mysql’]) scope :sorted, order(“percent_cpy desc”) scope :top, lamda {|1| limit(1)} end RemoteProcess.running.sorted.top(10) RemoteProcess.running.system.sorted.top(5) sample from Rails Antipatterns pp 37 2
89. rails g model {modelname} D
90. DSL ALL THE THINGS D
91. DIV-itis PHP-itis Java-isms D
92. 2 TYPOGRAPHIC REFACTORING http://naildrivin5.com/blog/2013/05/17/source-code-typography.html
93. M V C 2
94. <p> <% if location.present? %> Located in <%= @client.location %> <% else %> <span class="none">Location Unknown</span> <% end %> </p> 2
97. Untested Code D
98. FAT Controllers ONE CONTROLLER TO RULE THEM ALL... or not. D
100. So what do we do? THE KERNEL OF THE WAY
101. “ design patterns are suggested approaches seen in the wild. - B R I A N H O G A N ” T H I S B E A R S R E P E A T I N G :
103. “The best way to learn to write simple code is to write simple code! Patterns, like all forms of complexity, should be avoided until they are absolutely necessary. That’s the first thing beginners need to learn. Not the last thing. ” — Je Atwood c. 2005
104. “ You cannot say that you are correctly applying a design pattern unless you are confronting the problem that the pattern is supposed to solve – R U S S O L S O N ”
105. “...mediocre developers never even ask why. They just arrive at the first solution that works and keep plowing ahead.” — Je Atwood, c.2005
106. PATTERNS THEREFORE REMEMBER THAT IT’S NOT ABOUT USING
107. LANGUAGE it’s about speaking a
109. Let’s go theory! AND YET...
110. HAS NO NAME THE QUALITY OF A SPACE that
111. “Indeed this ageless character has nothing, in the end, to do with languages. The language, and the processes which stem from it, merely release the fundamental order which is native to us.” — The Timeless Way of Building, Chapter 27
112. “They do not teach us, they only remind us of what we know already, and of what we shall discover time and time again, when we give up our opinions, and do exactly what emerges from ourselves.” — The Timeless Way of Building, Chapter 27
113. “To make a building egoless, the builder must let go of all his willful images, and start with a void. You are able to do this only when you no longer fear that nothing will happen, and you can therefore afford to let go of your images. At this stage, the building’s life will come directly from your language.” — The Timeless Way of Building, Chapter 27
114. “Yet , at the very moment when you first relax, and let the language generate the buildings in your mind, you will begin to see how limited your language is. One place can have good patterns in it and be dead. Another place can be without the patterns which apply to it, and yet still be alive. ” — The Timeless Way of Building, Chapter 27
115. “The pattern ALCOVE–which first functioned as an intellectual crutch–is no longer necessary to you. You see reality directly, like an animal. You make the alcove as an animal might make an alcove–not because of the concept– but directly, simply because it is appropriate.” — The Timeless Way of Building, Chapter 27
117. The Three-book series
118. @boboroshi | @therailsview THANK YOU AthaydeWilliamsRailsView BOOK CODE FOR 25% OFF AT www.pragprog.com/titles/warv: john@meticulous.com