How to Gradually Update Your Code for PHP7.4 Compatibility - Improve Code Quality and Performance

M66 2025-07-27

Introduction

As technology continues to evolve, programming languages also receive frequent updates. PHP 7.4, the latest version, brings significant performance improvements and new features. Upgrading to this version can improve your code's efficiency and security. In this article, we will show you how to gradually update your code to make it compatible with PHP 7.4, along with best practices for this process.

Understanding New Features in PHP 7.4

Before starting the update, it is important to understand the new features and improvements in PHP 7.4. Here are some key highlights:

Typed Properties

PHP 7.4 introduces support for typed properties, allowing you to declare the type of class properties directly. This improves code readability and security. For example:

class Person {  
    public string $name;  
    public int $age;  
}

Arrow Functions

Arrow functions simplify the syntax of anonymous functions, making code more concise and readable. For example:

$numbers = [1, 2, 3, 4, 5];  
$squares = array_map(fn($n) => $n * $n, $numbers);

Preloading

PHP 7.4 introduces a preloading mechanism, allowing commonly used PHP files to be preloaded into memory, improving execution efficiency, especially for large applications and frameworks.

Updating PHP Version and Checking Warnings and Errors

First, ensure that your PHP environment is updated to version 7.4 or higher. After upgrading, run your existing test suite to check for any warnings or errors. PHP 7.4 made changes to some deprecated functions and syntax, which could affect your existing code.

Gradually Update and Fix the Code

When updating your code, break down the task into smaller parts based on the project’s module structure to minimize risk. Here are some key steps:

Update deprecated functions and syntax: Identify and replace deprecated functions and syntax in your code.
Add type declarations to properties: Add type declarations to class properties to improve code readability.
Replace anonymous functions: Replace `create_function()` with arrow functions for better readability.
Enable preloading: For projects with higher performance requirements, enable the preloading mechanism in PHP 7.4.

Conclusion

By gradually updating your code and fixing related issues, you can ensure that your codebase is compatible with PHP 7.4 while benefiting from performance and security enhancements. Before updating, it is essential to understand the new features in PHP 7.4 and run comprehensive tests. Regular code updates not only help maintain code quality but also improve development efficiency.