Packages, pub, and Everyday Tooling

Packages, pub, and Everyday Tooling

So far, you have written programs using only the Dart language itself. Real projects rarely stop there. They reuse code that other people wrote, and they use tools to manage that code. This chapter shows how.

What is a package?

A package is a bundle of ready-made Dart code that you can add to your project. If you need to make web requests, format dates, or draw charts, someone has probably published a package for it. Packages are stored in a central online catalog called pub.dev.

What is pub?

pub is Dart's package manager. A package manager is a tool that downloads packages, keeps track of their versions, and makes sure they work together. You use it through the dart pub command.

Every Dart project has a file called pubspec.yaml. This file lists the project's name and the packages it depends on. A dependency is a package your project needs.

Here is an example pubspec.yaml:

name: my_app
environment:
  sdk: ^3.0.0
dependencies:
  http: ^1.2.0

The line http: ^1.2.0 means "this project needs the http package, version 1.2 or later but not 2.0 or later." The caret symbol ^ sets that range.

To download the packages listed in your file, run:

dart pub get

Then you can use the package in your code:

import 'package:http/http.dart' as http;

Future<void> main() async {
  final response = await http.get(
    Uri.parse('https://example.com'),
  );
  print(response.statusCode);
}

What else does the tooling do?

The Dart SDK (the Software Development Kit, the toolkit that lets you build and run Dart programs) ships with a few commands you will use daily:

Two of these deserve a habit. Run dart format before you share code, so it always looks consistent. Run dart analyze often; it catches typos and type mistakes before your program ever runs.

How it fits together

100%

Show diagram source

flowchart LR
    A[pubspec.yaml] --> B[dart pub get]
    B --> C[(pub.dev)]
    B --> D[cached packages]
    D --> E[your code imports them]

Your everyday workflow

1. dart create my_app to start a project.
2. Add dependencies to pubspec.yaml.
3. dart pub get to fetch them.
4. Write code, then dart run to try it.
5. dart format and dart analyze to polish.