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
100k
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
How to bake a change
tastapod
PRO
0
230
The Most Dangerous Phrase
tastapod
PRO
7
5.8k
Rethinking Transformation
tastapod
PRO
1
280
CUPID - for joyful coding
tastapod
PRO
4
6.5k
agility at scale - a meeting of mindsets
tastapod
PRO
1
530
SWARMing into action
tastapod
PRO
0
360
Deliberate Advice
tastapod
PRO
3
1.3k
Governing Agile Delivery
tastapod
PRO
14
300
Complexity
tastapod
PRO
12
900
Other Decks in Technology
See All in Technology
Cloud Native Java with Spring Boot (CNCF Aarhus, April 2024)
thomasvitale
1
100
Signals Unleashed: The Full Guide
rainerhahnekamp
0
360
テストプロセスで大事にしていること #jasstnano
makky_tyuyan
0
110
「手動オペレーションに定評がある」と言われた私が心がけていること / phpcon_odawara2024
blue_goheimochi
2
320
ユーザーストーリーのレビューを自動化したみたの
bun913
1
310
Autonomous Database Cloud 技術詳細 / adb-s_technical_detail_jp
oracle4engineer
PRO
14
35k
キャラクター制御のためのプロンプト術 for LINE Bot
uezo
0
520
PHP"オレ"カンファレンスの告知
ysknsid25
0
360
レガシーをぶっ壊せ。AEONで始めるDevRelの話 / Qiita Night 2024-2-22
aeonpeople
3
150
プロトタイピングによる不確実性の低減 / Reducing Uncertainty through Prototyping
ohbarye
3
230
Next'24 事例セッションの紹介とクラウド資格を活用したキャリア形成について語りMuscle
yasumuusan
1
320
SREとその組織類型
tatsuo48
8
1.5k
Featured
See All Featured
Intergalactic Javascript Robots from Outer Space
tanoku
266
26k
Java REST API Framework Comparison - PWX 2021
mraible
PRO
18
6.9k
Put a Button on it: Removing Barriers to Going Fast.
kastner
58
3k
Learning to Love Humans: Emotional Interface Design
aarron
266
39k
Designing for humans not robots
tammielis
247
25k
JavaScript: Past, Present, and Future - NDC Porto 2020
reverentgeek
39
4.4k
Faster Mobile Websites
deanohume
297
30k
Build The Right Thing And Hit Your Dates
maggiecrowley
23
2k
No one is an island. Learnings from fostering a developers community.
thoeni
14
2.1k
Become a Pro
speakerdeck
PRO
10
4.5k
[Rails World 2023 - Day 1 Closing Keynote] - The Magic of Rails
eileencodes
1
1.3k
Exploring the Power of Turbo Streams & Action Cable | RailsConf2023
kevinliebholz
1
3.4k
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!