Gain insights into Dart's object-oriented features, explore extensions, enums, mixins, and asynchronous programming. Discover hands-on code practice to confidently apply Dart in your projects.

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dart2_7

Dart is a fully object-oriented, class-based, simple, and clean language. Google’s popular mobile framework, Flutter uses Dart language to implement high-quality native applications, so it’s recommended that you understand Flutter before beginning this course.

In this course, you will dive deep into Dart 2 language features while using interactive hands-on code playgrounds. This course will help you become confident with Dart extensions, enums, mixins, generics, libraries, asynchronous programming, class variables, callable classes, and generator functions.

By the end of this course, you will have a strong understanding of Dart principles, and you’ll be ready to start using this powerful language in your own projects.

Developing Web Applications with Dart

# Introduction

[Dart Generator Functions](https://dart.dev/guides/language/language-tour#generators) are used to generate a sequence of values on-demand in a lazy manner. Such a value sequence can be generated either synchronously or asynchronously. There are two types of built-in generator functions available to support both scenarios:

* **Synchronous Generator:** The synchronous generator function returns an [Iterable](https://api.dart.dev/stable/2.8.4/dart-core/Iterable-class.html) object. That means the values are generated first and then returned lazily on-demand by the function.

> **Iterable:** A collection of values or "elements", that can be accessed sequentially.

* **Asynchronous Generator:** The asynchronous generator function returns a [Stream](https://api.dart.dev/stable/2.8.4/dart-async/Stream-class.html) object. The sequence of values is generated on demand as each becomes available.

> **Stream:** A source of asynchronous data events.

With the help of an example, we can understand generator functions. We will generate numbers starting from a given number, 5 in our case, until 0, using generator functions. We will observe both ways (asynchronous and synchronous generators) to create this number sequence.

# Using `sync*` - synchronous generator

The function `Iterable<int> countDownFromSync(int num) sync*` takes a number as `num`, and sends out all numbers starting from `num` until 0. The synchronous generator function is marked with `sync*`. The values are returned using the `yield` keyword. The iterable `sequence` receives the number sequence and prints each number using a `for` loop. This number sequence is not generated until it has been accessed by the `for` loop.

`sync*` helps generate values in a synchronous manner. Note that the `Starting...` message is printed before for the loop's execution. The `DONE` message is executed at end.

In this lesson, you will learn about the generator functions.

Introduction

Dart Extensions

Dart Enums

Dart Mixins

Dart Generics

Dart Libraries

Asynchronous Programming In Dart

Miscellaneous

Next Steps

Generator Functions

Introduction