Flutter for Beginners

A single-file library

The most simplistic way to define a library is by adding all the interrelated code, that is, classes, top-level functions, and variables into one single file. For example, our previous Person library is as follows:

class Person {  String firstName;  String lastName;  PersonType _type;  Person({this.firstName, this.lastName});  String toString() => "($_type): $firstName $lastName";}enum PersonType { student, employee }class Student extends Person {  Student({firstName, lastName})      : super(firstName: firstName, lastName: lastName) {    _type = PersonType.student;  }}class Programmer extends Person {  Programmer({firstName, lastName})      : super(firstName: firstName, lastName: lastName) {    _type = PersonType.employee;  }}

There is nothing ...