Tweet
Tweet

Slide 1

Slide 1 text

SOLID - Architecture and Architectural Decisions Rivu Chakraborty 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social https://topmate.io/rivu

Slide 2

Slide 2 text

● India’s first GDE (Google Developer Expert) for Kotlin ● More than 12 years in the Industry ● Mobile Architect @ JioCinema ● Previously ○ Byju’s ○ Paytm ○ Gojek ○ Meesho ● Author (wrote multiple Kotlin books) ● Speaker ● Community Person ● Entrepreneur (?) 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Who am I? 󰞦

Slide 3

Slide 3 text

SOLID

Slide 4

Slide 4 text

SOLID Single Responsibility

Slide 5

Slide 5 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does Single Responsibility Mean 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social One class/function/object should focus on a single thing

Slide 6

Slide 6 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does Single Responsibility Mean 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Let’s say you have a viewmodel, and along with maintaining the state, the viewmodel is doing business logic. Is it Single Responsibility?

Slide 7

Slide 7 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does Single Responsibility Mean 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social There’s a Repository in our app, which is fetching data from the server and saving it in the local database while passing it onto the presentation layer (VM). Is it Single Responsibility?

Slide 8

Slide 8 text

SOLID Open-closed principle

Slide 9

Slide 9 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social classes, modules, and functions should be open for extension but closed for modification.

Slide 10

Slide 10 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social You have chat app. You only had text chat till now, you’re adding support for image sharing. So you add a flag (isImage) in your Chat class. Is it following OCP?

Slide 11

Slide 11 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Same example, you added an enum on MediaType instead of the boolean flag Is it following OCP?

Slide 12

Slide 12 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Same example, you added an enum on MediaType instead of the boolean flag. To add various data (like image url etc), you have to keep editing the Message class. Is it following OCP?

Slide 13

Slide 13 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social In the same chat app, you’re now adding Emoji 😃 support in Text Messages You Edited the TextMessage Class to do this. Is it following OCP?

Slide 14

Slide 14 text

SOLID Liskov Substitution Principle

Slide 15

Slide 15 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Objects of a superclass shall be replaceable with objects of its subclasses without breaking the application

Slide 16

Slide 16 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Same Example. You have chat app. You only had text chat till now, you’re adding support for various other types of messages. Instead of creating enum/flags. You decided to extend the existing Message class. Is it following Liskov Substitution?

Slide 17

Slide 17 text

SOLID Interface Segregation

Slide 18

Slide 18 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social No code should be forced to depend on methods it does not use. In other words, child classes should not be forced to implement/extend super class methods that it doesn’t require.

Slide 19

Slide 19 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Same Example. You have chat app. You only had text chat till now, you’re adding support for various other types of messages. You decided to better create an interface. Interface code in next slide.

Slide 20

Slide 20 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social interface IMessage { fun getMessageText(): String fun getMessageType(): MessageType fun getMediaUrl(): Url fun getMediaPreviewBase64(): Base64 fun getAudioVideoCodec(): Codec } //Is it following Interface Segregation?

Slide 21

Slide 21 text

SOLID Dependency Inversion

Slide 22

Slide 22 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social What Does it Mean? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social A class that uses a dependency, should not create it

Slide 23

Slide 23 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Dependency Inversion / Inversion of Control 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social It’s not only Dependency Injection

Slide 24

Slide 24 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Dependency Inversion / Inversion of Control 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Dependency Injection ● Constructor Injection ● Service Locator

Slide 25

Slide 25 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Dependency Injection 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Injecting a Dependency to a class / object at creation time, without any additional code in the class

Slide 26

Slide 26 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Dependency Injection 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Injecting a Dependency to a class / object at creation time, without any additional code in the class ● It’s mostly done with Annotation processors in Java / JVM

Slide 27

Slide 27 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Dependency Injection 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Injecting a Dependency to a class / object at creation time, without any additional code in the class ● It’s mostly done with Annotation processors in Java / JVM ● Example: Dagger / Hilt / Spring DI etc / Kotlin-Inject

Slide 28

Slide 28 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Constructor Injection 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Done with passing parameters in the constructor

Slide 29

Slide 29 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Constructor Injection 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Done with passing parameters in the constructor ● It’s also a type of Service Locator

Slide 30

Slide 30 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Constructor Injection 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Done with passing parameters in the constructor ● It’s also a type of Service Locator ● Vanilla implementation of Dependency Inversion is often done with Constructor Injection

Slide 31

Slide 31 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Service Locator 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Where a class has to request for a Dependency, but doesn’t directly create it

Slide 32

Slide 32 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Service Locator 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Where a class has to request for a Dependency, but doesn’t directly create it ● Example is Koin, where it uses Delegation to create dependencies

Slide 33

Slide 33 text

🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social Which one is Better? 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social ● Dependency Injection ● Constructor Injection ● Service Locator

Slide 34

Slide 34 text

Thank You Rivu Chakraborty 🌐https://www.rivu.dev/ youtube.com/@rivutalks @rivuchakraborty @rivu@androiddev.social https://topmate.io/rivu