Example of new features in PHP8: How to use attribute deduction and code to reduce duplicate code?

PHP8 is the latest version of the PHP programming language, officially released on November 26, 2020. As a language widely used in web development, PHP8 brings many exciting new features, including property inference and code reduction capabilities. This article will introduce some examples of how to use these new features.

1. Attribute Derivation

In past PHP versions, we needed to manually define getter and setter methods for class attributes to access and modify attributes. But in PHP8, we can use attribute deduction to simplify this process.

Consider the following example, we create a Person class containing two attributes: name and age:

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

    public function getName(): string {
        return $this->name;
    }

    public function setName(string $name): void {
        $this->name = $name;
    }

    public function getAge(): int {
        return $this->age;
    }

    public function setAge(int $age): void {
        $this->age = $age;
    }
}

In PHP8, we can use attribute deduction to simplify this code:

class Person {
    public function __construct(
        public string $name,
        public int $age,
    ) {}
}

By using property deduction, we can define the properties of the class directly in the constructor and omit the definition of the getter and setter methods. Now, we can instantiate the Person class and access the properties in the following way:

$person = new Person('John Doe', 25);
echo $person->name;  // 输出：John Doe
echo $person->age;  // 输出：25

As you can see, using property derivation greatly simplifies the code structure and reduces the writing of redundant code.

2. Reduce code duplication

In PHP8, we have also introduced some new functions and functions that can be used to reduce code duplication. Two of these features will be introduced below: named parameters and the null coalescing operator.

1. Named parameters

Named parameters mean that when a function or method is called, parameter values ​​can be passed by specifying parameter names. This reduces dependence on parameter location and improves code readability and maintainability.

Consider the following example, we have a function that calculates the sum of two numbers:

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

echo sum(5, 10);  // 输出：15

In previous versions, we had to pass parameter values ​​in the order in which the function was defined. But in PHP8, we can use named parameters to call functions:

echo sum(b: 5, a: 10);  // 输出：15

By specifying parameter names, we can pass parameter values ​​in any order, making the code more intuitive and readable.

2. null coalescing operator

In PHP, we often need to check if a variable is null and provide a default value if it is null. In previous versions, we usually used the ternary operator or if statement to achieve this function.

Consider the following example where we need to check if a variable is null and provide it with a default value:

$username = isset($_GET['username']) ? $_GET['username'] : 'Guest';

In PHP8, we can use the null coalescing operator (??) to simplify this Code snippet:

$username = $_GET['username'] ?? 'Guest';

If $_GET['username'] is not null, assign its value to $username; otherwise, assign 'Guest' to $username.

In addition to the above examples, PHP8 also introduces some other new features, such as match expressions, static return type declarations, etc. These features have greatly improved the functionality and flexibility of PHP.

Summary:

This article introduces two new features in PHP8: attribute derivation and code reduction to duplicate code. Property derivation makes defining class properties more concise and intuitive, reducing the writing of redundant getter and setter methods. The two functions of named parameters and null coalescing operator improve the readability and maintainability of the code. With the release of PHP8, we will be able to write concise and efficient PHP code more easily.

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