Скачать или смотреть Understanding the ObservableList vs @ observable List in MobX

Dive into the key distinctions between `ObservableList`, `@ observable ObservableList`, and `@ observable List` in MobX and learn how these concepts affect your Flutter/Dart applications.
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Understanding the ObservableList vs @ observable List in MobX: A Beginner's Guide

MobX is a popular state management library that is widely used in Flutter and Dart applications. One common question that beginners encounter, especially those new to MobX, is understanding the differences between ObservableList, @ observable ObservableList, and @ observable List. In this guide, we aim to clarify these concepts and help you make informed decisions while implementing them in your projects.

What is an Observable in MobX?

Before diving into the distinctions between ObservableList and the various forms of @ observable lists, it's important to understand what observables are in MobX.

Observables are special variables that can automatically notify the UI when their values change.

They help you create reactive apps by ensuring that when the underlying data changes, the user interface (UI) reflects those changes immediately and seamlessly.

Now, let’s break down the specific types of lists you may encounter in MobX.

The Three List Types Explained

1. ObservableList<Todo> todos;

Definition: A standard ObservableList in MobX, which will be observed.

Behavior: It only activates observers when you modify the list itself (like adding or removing items). However, if you assign a new list to the variable todos, the UI will not respond to this change.

Use Case: Use this when you’re focusing on the operations on the list but not necessarily changing the reference of the list itself.

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2. @ observable ObservableList<Todo> todos;

Definition: This signifies that todos not only holds an observable list but also marks the variable itself as an observable property.

Behavior: Observers are activated whenever you either modify the content of the list or assign a new list entirely. This means that any change, whether it's a mutation of the list's content or reassignment, triggers a UI update.

Use Case: Choose this option when you want your UI to respond to both types of changes related to the list.

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3. @ observable List<Todo> todos;

Definition: In this case, todos is a regular Dart list that is marked as observable.

Behavior: The observable aspect only comes into play when you reassign the list (i.e., when you create a new list and assign it to todos). Modifying the contents of the existing list won't trigger a UI update.

Use Case: This is suitable if you want to monitor changes in the reference of the list while performing internal modifications without affecting the UI directly.

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Summary

Understanding the differences between ObservableList, @ observable ObservableList, and @ observable List is crucial for effectively managing state in your Flutter and Dart applications using MobX. Here’s a quick recap:

ObservableList<Todo> todos;: Only triggers on modifications to the list, not reassignments.

@ observable ObservableList<Todo> todos;: Triggers on both modifications and reassignments.

@ observable List<Todo> todos;: Triggers only on reassignments, not modifications.

By understanding these differences, you can take full advantage of MobX's capabilities to build responsive and efficient applications. Happy coding!