Solid-Principles

S - Single Responsibility

• Each class has one and only one responsibility.
• AuthenticationService class only responsible for signIn and signOut

data class User(var email: String, var password: String)

class AuthenticationService() {

fun signIn() {}
fun signOut() {}

}

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O - Open Closed Principle

• Open-Closed Principle
• Class should be open for Extension(Adding features)
• but, Closed for modification

Example one using Inheritance:-

open class Logger { open fun logErrors(err: String) { print("error found - $err") } }

class CustomLogger : Logger() { override fun logErrors(err: String) { print("custom error found - $err") } }

Example two using Interface:-

interface Errors { fun printErrors() }

class CustomErrors : Errors { override fun printErrors() { print("errors") } }

class ApiErrors : Errors { override fun printErrors() { TODO("Not yet implemented") } }

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Reference source:-

https://www.youtube.com/watch?v=t8VTLxMsufU

https://medium.com/the-android-caf%C3%A9/solid-principles-the-kotlin-way-ff717c0d60da