Converting a Simple Class to an Extension in Dart

Описание: Learn how to convert a simple Dart class for number conversion into an extension method to enhance your Flutter applications.
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This video is based on the question https://stackoverflow.com/q/63975373/ asked by the user 'DolDurma' ( https://stackoverflow.com/u/1830228/ ) and on the answer https://stackoverflow.com/a/63975435/ provided by the user 'Didier Prophete' ( https://stackoverflow.com/u/3268072/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Converting a Simple Class to an Extension in Dart: A Practical Guide

When you're programming in Dart, especially within the Flutter framework, you may come across situations where you want to extend the functionality of existing types, such as String. In this post, we will explore how to convert a simple class designed for number conversion into a Dart extension. This will allow you to conveniently use this functionality directly on String objects.

The Problem: Number Conversion in Dart

Consider a situation where you need to convert English numbers (0-9) to their corresponding Farsi numerals (۰-۹) and vice versa. Initially, you might have a class like this:

[[See Video to Reveal this Text or Code Snippet]]

While this class works perfectly, it might be more idiomatic in Dart to use extension methods, which allow you to attach new functionality to existing types, making your code more readable and expressive.

The Solution: Create an Extension for Conversion

To convert the above Strings class into a String extension, we will create an extension that allows us to call the number conversion directly on any String instance. Here’s how to do it step by step:

Step 1: Define the Extension

We will define an extension called ConvertNum on the String type.

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Understand the Code

Using this: In Dart extensions, this refers to the instance of the object the method is called on. This allows us to manipulate the string directly.

Conversion Logic: The logic remains the same: we loop over the english and farsi arrays. Depending on the value of the reverse parameter, we replace the characters accordingly.

Return Value: The method returns the converted string.

Step 3: Usage Example

Now that we have defined our extension, you can use it as follows:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By converting your simple class into an extension method, you not only make your code cleaner and more intuitive, but you also embrace the powerful capabilities of Dart's extensions. It encourages a more functional style of programming, making your Flutter applications more elegant and maintainable.

Now, you can use the changeNum method easily on any String to perform number conversions, enriching your coding experience in Dart!