The new optional strict mode in PHP7: How to improve code quality and performance?

An optional strict mode has been added to PHP7. This new feature can help developers improve the quality and performance of their code. This article will help readers understand how to use strict mode to improve code quality and performance by introducing the characteristics and specific usage examples of strict mode.

1. Characteristics of strict mode
Strict mode is a new feature of PHP7. It forces developers to follow a more standardized programming method through a series of error detection and warning mechanisms. Strict mode mainly includes the following features:

1. Strict type checking: In strict mode, PHP will check type matching more strictly, reminding developers to avoid implicit conversion and type inconsistency errors.
2. Declare scalar types: In strict mode, developers are allowed to declare the specific types of function parameters and return values, which can express the intent of the function more clearly and avoid incorrect parameter passing.
3. Type declaration: In strict mode, type declarations can be made for the parameters and return values ​​of class attributes and methods to ensure the robustness and maintainability of the code.
4. Null value checking: In strict mode, a null value will be considered an incorrect data, and developers must explicitly handle or avoid using null values.
5. Constant declaration: Strict mode requires developers to use the define() function to declare constants instead of using the keyword const.

2. How to improve code quality and performance

1. Forced type checking
   In strict mode, we can ensure the data type by declaring the types of parameters and return values consistency. The following is an example:

declare(strict_types=1);

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

$result = add(1, 2); // 正确的用法
$result = add('1', 2); // 会被报错

By forcing type checking, we can avoid errors caused by type conversion and improve code quality and maintainability.

2. Type declaration
   In strict mode, we can use type declarations to ensure that the parameters and return values ​​of methods and properties are of the correct type. The following is an example:

declare(strict_types=1);

class MyClass {
    private int $id;
    
    public function setId(int $id): void {
        $this->id = $id;
    }
    
    public function getId(): int {
        return $this->id;
    }
}

$myObj = new MyClass();
$myObj->setId(1); // 正确的用法
$myObj->setId('1'); // 会被报错

Through type declaration, we can clearly define the acceptable parameter and return value types of properties and methods to avoid incorrect calls and uses.

3. Null value checking
   Strict mode requires developers to explicitly handle null values. You can use the null value merging operator (??) or the null merging operator (??) to handle null values. value. The following is an example:

declare(strict_types=1);

function getUserFullName(?string $firstName, ?string $lastName): string {
    $fullName = $firstName ?? '';
    $fullName .= ' ' . $lastName ?? '';
    
    return trim($fullName);
}

echo getUserFullName('John', 'Doe'); // 输出 "John Doe"
echo getUserFullName(null, 'Doe'); // 输出 "Doe"

By explicitly handling null values, we can avoid errors caused by unhandled null values ​​and improve the robustness of the code.

4. Constant declaration
   In strict mode, it is recommended to use the define() function to declare constants instead of using the keyword const. The following is an example:

declare(strict_types=1);

define('SITE_NAME', 'My Website');
const ITEM_PRICE = 10;

By using the define() function to declare constants, we can ensure the scope and visibility of the constants and improve the reliability of the code.

To sum up, strict mode is an important new feature in PHP7, which can help developers improve the quality and performance of their code. Through features such as forced type checking, type declaration, null value checking, and constant declaration, we can avoid some common programming errors and improve the robustness and maintainability of the code. Therefore, reasonable use of strict mode can make our PHP code more standardized, reliable and efficient.

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