Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Why Every Element of SOLID is Wrong
Search
Daniel Terhorst-North
PRO
January 20, 2017
Technology
130
110k
Why Every Element of SOLID is Wrong
Five minute Ignite-style talk from PubConf London 2016
Daniel Terhorst-North
PRO
January 20, 2017
Tweet
Share
More Decks by Daniel Terhorst-North
See All by Daniel Terhorst-North
The best programmer I know
tastapod
PRO
2
76
How to bake a change
tastapod
PRO
0
370
The Most Dangerous Phrase
tastapod
PRO
7
6k
Rethinking Transformation
tastapod
PRO
1
310
CUPID - for joyful coding
tastapod
PRO
4
6.9k
agility at scale - a meeting of mindsets
tastapod
PRO
1
550
SWARMing into action
tastapod
PRO
0
370
Deliberate Advice
tastapod
PRO
3
1.4k
Governing Agile Delivery
tastapod
PRO
14
300
Other Decks in Technology
See All in Technology
Next.js のページ遷移を全力で止める
ypresto
6
3.2k
リアルお遍路+SORACOM IoT
ozk009
1
140
株式会社EventHub・エンジニア採用資料
eventhub
0
2.9k
言葉は感情の近似値である。その感情と言葉の誤差を最小化しよう ~コミュニケーションにおけるアナログ/デジタル変換の課題に立ち向かう~
nktamago
0
220
より快適なエラーログ監視を目指して
leveragestech
4
1.4k
あなたの知らないiOS開発の世界
recruitengineers
PRO
3
180
『GRANBLUE FANTASY: Relink』最高の「没入感」を実現するカットシーン制作手法とそれを支える技術
cygames
1
140
AI活用したくてもできなかった不動産SaaSの今とこれから
nealle
0
330
『GRANBLUE FANTASY Relink』キャラクターの魅力を支えるリグ・シミュレーション制作事例
cygames
0
120
Functional TypeScript
naoya
11
4.8k
GC24 Recap: Interface Internals
task4233
0
130
Mocking in Rust Applications
taiki45
1
410
Featured
See All Featured
Design by the Numbers
sachag
277
19k
10 Git Anti Patterns You Should be Aware of
lemiorhan
653
58k
The Mythical Team-Month
searls
218
43k
Building an army of robots
kneath
302
42k
Practical Tips for Bootstrapping Information Extraction Pipelines
honnibal
PRO
5
480
The Invisible Customer
myddelton
119
13k
From Idea to $5000 a Month in 5 Months
shpigford
379
46k
How to name files
jennybc
75
98k
Infographics Made Easy
chrislema
239
18k
CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again
sstephenson
157
15k
VelocityConf: Rendering Performance Case Studies
addyosmani
322
23k
Being A Developer After 40
akosma
84
590k
Transcript
Why Every Single Element of SOLID is Wrong! Dan North
@tastapod
Single Responsibility Open/Closed Liskov Substitution Interface Segregation Dependency Inversion
Single Responsibility Principle “one reason to change” “only do one
thing”
Single Responsibility Principle What is a single responsibility anyway? ETL:
three responsibilities or one? How can you predict what is going to change? Pointlessly Vague Principle
Single Responsibility Principle Simple code is easy to reason about
Can easily do several related things Refactor until it Fits In Your Head Write simple code
Open-Closed Principle Open for extension, closed for modification “When requirements
change, extend behaviour by adding new code, not changing code that works”
Open-Closed Principle Open for extension, closed for modification “When requirements
change, the existing code is now wrong! so replace it with code that works” Cruft Accretion Principle
Open-Closed Principle Simple code is easy to change Simple code
is easy to test Simple code is both open and closed Write simple code!
Liskov Substitution Principle “Strong behavioural subtyping” Substitution with a subtype
preserves all “desirable properties” of the original type “Provably undecidable” but useful
Liskov Substitution Principle “There is nothing quite so useless, as
doing with great efficiency, something that should not be done at all.” Stuck in is-a and has-a modelling mindset Drucker’s Warning Principle
Liskov Substitution Principle What about acts-like-a, can-be-used-as-a? Composition is simpler
than inheritance Try to avoid object hierarchies altogether Write simple code!
Interface Segregation Principle Many small interfaces are better than one
big object Design small, role-based interfaces No client depends on methods it doesn’t use
Interface Segregation Principle Practically anything is better than one big
object Design small, role-based classes No client depends on methods it doesn’t use Stable Door Principle This is already true!! —>
Interface Segregation Principle Don’t write big objects in the first
place! Write code that Fits In Your Head If a class needs lots of interfaces, simplify the class! Write simple code!
Dependency Inversion Principle High-level modules should not depend on lower-level
modules Abstractions (e.g. interfaces) should not depend on details (e.g. concrete implementations)
Dependency Inversion Principle Reuse is overrated, design for use! DIP
leads to a different kind of dependency, dependency on DI frameworks! Wrong Goal Principle
Dependency Inversion Principle See how far you get combining simple
classes new is the new new! Assemble into small components that Fit In Your Head Write simple code!
Single Responsibility Open/Closed Liskov Substitution Interface Segregation Dependency Inversion
Single Responsibility Open/Closed Liskov Substitution Interface Segregation Dependency Inversion Too
much to remember!
Single Responsibility Open/Closed Liskov Substitution Interface Segregation Dependency Inversion Write
simple code!