How to refactor PHP5.6 code to adapt to the new syntax and features of PHP7.4?

How to refactor PHP 5.6 code to adapt to the new syntax and features of PHP 7.4?

With the continuous development of PHP, new versions bring many new syntax and features, and PHP 7.4 is one of the major versions. These new syntax and features can improve the performance and readability of your code. Therefore, when we migrate from PHP 5.6 to PHP 7.4, we should refactor our code to adapt to the new version.

Here are some ways to refactor your PHP 5.6 code to accommodate the new syntax and features of PHP 7.4.

1. Type declarations

PHP 7.4 introduces strict type declarations for function parameters and return values. In PHP 7.4, we can use the following syntax to declare the types of parameters and return values:

function add(int $a, int $b): int {
    return $a + $b;
}

In PHP 5.6, we usually use type annotations to express the types of parameters and return values. When refactoring code, we should convert these type annotations into strict type declarations.

2. Declaring attribute types

In PHP 7.4, we can specify types for attributes of classes. For example:

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

In PHP 5.6, we usually assign values ​​to properties in the constructor and use type annotations. When refactoring the code, we should convert the type annotations for these properties into property type declarations.

3. Null coalescing operator and null-safe operator

PHP 7.4 introduces the null coalescing operator (??) and null-safe operator (?.) , these operators simplify code and enhance security.

The null coalescing operator is used to check whether a variable is null. If it is null, it returns the default value. For example:

$name = $_GET['name'] ?? 'Unknown';

In PHP 5.6, we usually use conditional statements to check whether a variable is null. When refactoring our code, we can use the null coalescing operator to simplify conditional statements.

The null-safe operator is used to access properties and methods of variables that may be null. For example:

$length = $person->address?.length;

In PHP 5.6, we usually use conditional statements to check whether a variable is null. When refactoring code, we can use null-safe operators to simplify conditional statements.

4. Arrow Functions

PHP 7.4 introduced arrow functions, which provide a more concise syntax for defining anonymous functions. For example:

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

In PHP 5.6, we usually use create_function() to create anonymous functions. When refactoring code, we can use arrow functions to simplify the definition and calling of anonymous functions.

5. Type Inference

In PHP 7.4, variable type inference has been enhanced. For example, in a loop, the type of an array can be automatically inferred:

$numbers = [1, 2, 3, 4, 5];
foreach ($numbers as $number) {
    echo $number; // 可以推断 $number 是整数类型
}

In PHP 5.6, we usually use type annotations to specify the type of an array. When refactoring the code, we can take advantage of the type inference feature of PHP 7.4 to simplify the code.

By refactoring PHP 5.6 code to adapt to the new syntax and features of PHP 7.4, we can improve the performance and readability of the code. Before refactoring the code, we should first understand the new syntax and features, and then gradually refactor the code according to the requirements of the new version. Refactoring code not only improves the quality of the code, but also keeps our code up to date.

Reference:

1. PHP official documentation - https://www.php.net/manual/en/migration70.new-features.php

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