Day 5 · Advanced Classes — Modifiers, Factory, Mixins
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Day 5

Advanced Classes — Modifiers, Factory, Mixins

Go deep on OOP — class modifiers (abstract, base, interface, final, sealed), factory constructors, mixins with on keyword, enhanced enums, and extension methods. Problem-first teaching throughout.

Topics Covered
6 Class Modifiersabstract, base, interfacefinal, sealed, factoryMixins with & onEnhanced EnumsExtension Methods3 Quizzes + Payment System Project
Resources
Dart Class Modifiers Factory Constructors Mixins Extension Methods DartPad
Assignments
1
Complete all 3 in-slide quizzes
2
Build the Payment System project on DartPad
3
Make Payment sealed with 5 subtypes (Cash, Card, eSewa, Khalti, IME)
4
Add factory Payment.fromType(String) constructor
5
Create mixin Loggable used across payment classes
6
Add enhanced enum OrderStatus with icon + color fields
7
Create extension on int for .rupees and .percentOf(total)
8
Push to flutter-tr06 with meaningful commits via PR