Pattern Language for Rubyists (Rev.2)

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Pattern Language for Rubyists @irohiroki

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Overview “Pattern Language” Pattern Language and software Whether it matters to us

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@irohiroki "HJMFDPBDI 8FCEFWFMPQFS l3BJMT%FWFMPQNFOU1BUUFSOTz "TJBO1-P1

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A pattern language is a method of describing good design practices within a field of expertise. – Wikipedia, “Pattern language”

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Christopher Alexander

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Quality Without A Name Picture by Lies Thru a Lens 

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Beyond its elements each building is defined by certain patterns of relationships among the the elements. –Christopher Alexander, “The Timeless Way of Building”

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“Courtyard which live” –Christopher Alexander et al, “A Pattern Language”

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And each law of pattern is itself a pattern of relationships among still other laws, which are themselves just patterns of relationships again. –Christopher Alexander, “The Timeless Way of Building”

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–Christopher Alexander, “A City is not a Tree”

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From a mathematical point of view, the simplest kind of language is a system which contains two sets: 1. A set of elements, or symbols. 2. A set of rules for combining these symbols. –Christopher Alexander, “The Timeless Way of Building”

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“Pattern Language”

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Natural Language Pattern Language Words Patterns Rules of grammar and meaning which give connections Patterns which specify connections between patterns Sentences Buildings and places –Christopher Alexander, “The Timeless Way of Building”

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Each pattern is a rule which describes what you have to do to generate the entity which it defines. –Christopher Alexander, “The Timeless Way of Building”

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Picture by Liz Castro

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The specific patterns out of which a building a town is made may be alive or dead. To the extent they are alive, they let our inner forces loose, and set us free; but when they are dead they keep us locked in inner conflict. –Christopher Alexander, “The Timeless Way of Building”

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Dead Pattern

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Living Pattern

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“Window Place” –Christopher Alexander et al, “A Pattern Language”

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1. Independent Regions 2. Distribution of Towns 3. City Country Fingers 4. Agricultural Valleys 5. Lace of Country Streets 6. Country Towns 7. The Countryside Pattern #1~7

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105. South Facing Outdoors 106. Positive Outdoor Space 107. Wings of Light 108. Connected Buildings 109. Long Thin House Pattern #105~109

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197. Thick Walls 198. Closets Between Rooms 199. Sunny Counter 200. Open Shelves 201. Waist-high Shelf 202. Built-in Seats Pattern #197~202

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You can use it to design a house for yourself, with your family; or to work with other people to design an office or a workshop or a public building like a school. –Christopher Alexander et al, “A Pattern Language”

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Back to the binary world…

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Discoverer of Pattern Language Kent Beck eXtreme Programming Ward Cunningham Wikiwiki “Technical debt”

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The Starting Point of Software Patterns - youtu.be/_V0kVOLOCrY

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A Small Pattern Language for GUI 1. Window Per Task 2. Few Panes Per Window 3. Standard Panes 4. Short Menus 5. Nouns and Verbs

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“We presented these patterns to a team of application specialists writing a specification for a special purpose programming environment. Without detailed understanding of any of Smalltalk's interface mechanisms (MVC for example) they were able to specify very reasonable interfaces after one day of practice.” –Kent Beck, Ward Cunningham, “Using Pattern Languages for Object-Oriented Programs”

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Do you have a pattern language in your mind?

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We have written this book as a first step in the society-wide process by which people will gradually become conscious of their own pattern languages, and work to improve them. –Christopher Alexander et al, “A Pattern Language”

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@irohiroki @ukstudio @mochiz @tatsuoSakurai @kei_s @moro @ttakuru88 @takkanm

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How we found Rails dev. patterns 1. Kick off meeting 2. Discuss development knacks (pristine “patlets”) 3. Group patlets in KJ-method 4. Rewrite the groups in pattern form 5. Find sequence of patterns (WIP) 6. Refine the patterns (WIP)

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Rails Development Patterns 18 patlets / 6 patterns in form Reviewed at AsianPLoP 2015 Work in progress on GitHub (rails- patterns/rails_dev_patterns)

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“ެࣜ৘ใ”  (Ofﬁcial Information) Context: You are going to use a new or unfamiliar feature of Rails. Problem: You may copy and paste misinformation from the web. Solution: Refer the official Rails guide or the API reference.

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“ެવͷSQL”  (Not-so-Secret SQL) Context: You are going to use an ActiveRecord to make a database query. Problem: You may make ineffective, wasteful queries. Solution: Confirm what SQL the ActiveRecord generates.