The pub packaging system is a great resource for sharing finished packages online. If we want to keep a package local and private, we can create it locally and use it in much the same manner.
The package project is structured in a similar manner to a web application project, with a pubspec.yaml file being the main project file. Instead of a web folder, there is a lib folder containing the simple_dialog.dart file that declares our library and defines what is exposed outside the project:
This file contains any classes, functions, and references to other files—in this case, the two files in the src folder. The first line in simple_dialog.dart with the keyword library states the name and declares that this is a library. Note that it is not surrounded by any quotation marks:
library simple_dialog; import 'dart:html'; part 'src/dialog_base.dart'; part 'src/prefabs.dart';
The next section contains the imports required for all the files that are...