How to create and publish your own Dart package

Are you a Dart developer looking to share your code with the world? Do you want to know how to create and publish your own Dart package? Look no further! In this article, we'll show you everything you need to know to get started.

What is a Dart package?

First things first, what exactly is a Dart package? A Dart package is a collection of Dart code that can be reused across projects. It can contain code for various purposes, such as utility functions, UI components, or APIs. Packages are managed using Pub, the official package manager for the Dart programming language.

Setting up your workspace

Before we dive into creating a package, let's make sure your workspace is set up correctly. You'll need to have Dart installed on your machine. You can find the latest version of Dart here.

You'll also need to install the Dart SDK. The Dart SDK comes with Pub, so you don't need to install it separately. You can find instructions for installing the Dart SDK here.

Creating your package

Now that your workspace is set up, it's time to create your package. The easiest way to create a package is using the dart create command, which generates a basic package structure for you.

To create a package, run the following command in your terminal:

$ dart create --template=package my_package

This will create a new directory called my_package, which contains the basic package structure.

Package structure

Let's take a look at the structure of the my_package directory:

my_package/
├─ .gitignore
├─ .packages
├─ CHANGELOG.md
├─ LICENSE
├─ README.md
├─ analysis_options.yaml
├─ example/
│  ├─ README.md
│  ├─ bin/
│  │  └─ my_package.dart
│  └─ lib/
│     └─ my_package.dart
├─ lib/
│  └─ my_package.dart
├─ pubspec.lock
├─ pubspec.yaml
└─ test/
   └─ my_package_test.dart

Here's what each of these files and directories does:

• .gitignore: A file telling Git which files to ignore when committing.
• .packages: A file that lists the locations of all the packages used by your package.
• CHANGELOG.md: A file for documenting changes to your package.
• LICENSE: A file containing the license for your package.
• README.md: A file containing information about your package.
• analysis_options.yaml: A file containing analysis options for your package.
• example/: A directory containing an example usage of your package.
• example/README.md: A file containing information about the example usage.
• example/bin/: A directory containing an example command-line application.
• example/lib/: A directory containing an example library.
• lib/: A directory containing the source code for your package.
• pubspec.yaml: A file containing metadata for your package.
• pubspec.lock: A file containing the exact versions of the packages used by your package.
• test/: A directory containing unit tests for your package.

Adding functionality

Now that we've created our basic package structure, it's time to add some functionality. Let's create a simple utility function that calculates the area of a rectangle.

Open the my_package/lib/my_package.dart file and modify it to look like this:

/// Calculates the area of a rectangle.
num calculateArea(num width, num height) {
  return width * height;
}

That's it! We now have a simple utility function that calculates the area of a rectangle.

Testing your package

It's important to test your package to make sure everything works as expected. The my_package package comes with a sample test file to get you started.

To run the sample tests, run the following command in your terminal:

$ dart test

This will run the tests in the my_package/test/my_package_test.dart file. If everything is working correctly, you should see output like this:

00:00 +0: my_package_test
All tests passed!

Adding dependencies

Most packages will have dependencies on other packages. You can add dependencies to your package using the dependencies section in the pubspec.yaml file.

Let's say we want to use the crypto package to add some cryptographic functionality to our package. Open the pubspec.yaml file and modify it to look like this:

name: my_package
version: 0.0.1

dependencies:
  crypto: ^3.0.0

Save the file and run the following command in your terminal:

$ dart pub get

This will download the crypto package and add it to your package's dependencies.

Now you can use the crypto package in your code. For example, let's generate a random UUID using the crypto package:

import 'package:crypto/crypto.dart';

String generateUuid() {
  var randomBytes = new List<int>.generate(16, (i) => _random.nextInt(256));
  var uuid = new Uuid.fromBuffer(randomBytes);
  return uuid.toString();
}

Publishing your package

Now that you've created your package and added some functionality, it's time to publish it for the world to use!

Before you publish your package, it's a good idea to make sure everything is working correctly, and that all tests pass. To run your tests, use the following command:

$ dart test

When everything is working correctly, it's time to publish your package. First, you'll need to create an account on pub.dev. Once you have an account, run the following command in your terminal:

$ dart pub publish

This will upload your package to pub.dev. Congratulations, you've just published your first Dart package!

Conclusion

In this article, we've shown you how to create and publish your own Dart package. We've covered the basics of package structure, adding functionality, testing, adding dependencies, and publishing.

Now that you know how to create and publish a Dart package, the sky's the limit! With Dart's vibrant ecosystem, there's never been a better time to start creating and sharing your own packages.

Additional Resources