5.14. Introduction to Object Oriented Programming in Dart: Asynchronous Programming

Página 70

Object-oriented programming (OOP) is a programming paradigm that uses objects and their interactions to design applications and computer programs. Dart, the programming language used with Flutter, is an object-oriented language. In this chapter, we'll explore object-oriented programming in Dart, and more specifically, asynchronous programming.

1. Basic Object Oriented Programming (OOP) concepts

Before we dive into asynchronous programming, it's important to understand some basic OOP concepts in Dart. OOP in Dart is centered around classes and objects. A class is like a blueprint for creating objects. It defines a set of properties (called instance variables) and methods (functions that belong to a class).

An object is an instance of a class. It has a state (defined by its instance variables) and behavior (defined by its methods). In Dart, you create an object using the 'new' keyword followed by the class name and parentheses.

2. Asynchronous Programming

Now that we have a basic understanding of OOP in Dart, let's explore asynchronous programming. Asynchronous programming is a style of programming that is used to improve the performance of a program through efficient use of its runtime and system resources.

In a synchronous program, operations are performed one after the other. If an operation takes too long to complete (for example, a network request), the entire program is blocked or frozen until the operation completes. This can result in a poor user experience, especially in UI applications where responsiveness is crucial.

Asynchronous programming solves this problem by allowing the program to continue performing other operations while waiting for the long-running operation to complete. In Dart, asynchronous programming is facilitated by the use of 'Future', 'async' and 'await'.

2.1 Future

A 'Future' in Dart represents a potential value or error that will be available at some point in the future. It's like a promise that eventually there will be a value. You can think of 'Future' as the return of an asynchronous operation.

For example, a function that makes a network request might return a 'Future'. The 'Future' will complete when the network request completes. If the request is successful, the 'Future' is completed with the resulting value. If the request fails, 'Future' completes with an error.

2.2 async and await

'async' and 'await' are keywords in Dart that are used to work with 'Futures'. The 'async' keyword is used to declare an asynchronous function. An async function is a function that can perform async operations (that is, operations that return a 'Future').

The 'await' keyword is used inside an async function to pause the execution of the function until a 'Future' completes. When 'Future' completes, function execution continues. If 'Future' completes with a value, 'await' will return that value. If 'Future' completes with an error, 'await' will throw that error.

By combining 'async' and 'await', you can write asynchronous code that looks and behaves like synchronous code. This makes the code easier to read and understand.

Conclusion

Object-oriented programming and asynchronous programming are fundamental concepts in Dart and Flutter. Understanding these concepts will allow you to build more efficient and responsive apps. Remember, practice is the key to becoming proficient in these techniques, so keep exploring and experimenting.

Next page of the Free Ebook:

715.15. Introduction to Object Oriented Programming in Dart: Unit Testing