PHP Function Design Patterns and Best Practices

Understand PHP functional design patterns and best practices: Design Patterns: Factory Pattern: Allows the creation of different types of objects at runtime. Singleton pattern: Ensure that a class has only one instance. Best Practice: Naming Convention: Use clear, concise function names. Single Responsibility Principle: A function performs only one task. Parameter type hints: Specify parameter and return value types. Default values ​​are optional parameters: increased flexibility. Unit testing: Verify the behavior of a function.

PHP Function Design Patterns and Best Practices

A function is a block of code in PHP that performs a specific task. In order to write maintainable, extensible, and reusable code, it's crucial to understand functional design patterns and best practices.

Design pattern

1. Factory pattern

Factory pattern creates instances of objects without specifying their concrete classes. This allows created classes to be changed at runtime.

abstract class ShapeFactory
{
    abstract public function createShape(string $shapeType): Shape;
}

class CircleFactory extends ShapeFactory
{
    public function createShape(string $shapeType): Shape
    {
        if ($shapeType === 'circle') {
            return new Circle();
        }
        throw new InvalidArgumentException();
    }
}

$circleFactory = new CircleFactory();
$circle = $circleFactory->createShape('circle');

2. Singleton pattern

The singleton pattern ensures that only one instance of a class can be created. This is typically used to create global access objects.

class Database
{
    private static $instance;

    private function __construct() {}

    public static function getInstance(): Database
    {
        if (self::$instance === null) {
            self::$instance = new Database();
        }
        return self::$instance;
    }
}

// 此处只能获取 Database 的一个实例
$db1 = Database::getInstance();
$db2 = Database::getInstance();
if ($db1 === $db2) {
    echo '同一实例';
}

Best Practices

1. Naming Convention

Use clear and concise function names that reflect the function of the function .

function calculateArea(Shape $shape)

2. Single Responsibility Principle

A function is only responsible for one task. Complex logic should be broken down into smaller functions.

function calculateArea(Shape $shape)
{
    switch ($shape->getType()) {
        case 'circle':
            return pi() * $shape->getRadius() ** 2;
        case 'rectangle':
            return $shape->getWidth() * $shape->getHeight();
    }
}

3. Parameter type hints

Specify the types of function parameters and return values ​​to improve code readability and security.

function calculateArea(Shape $shape): float

4. Default values ​​

Provide default values ​​for optional parameters to increase flexibility and reusability.

function calculateArea(Shape $shape, float $scale = 1.0): float

5. Unit testing

Write unit tests to verify that functions behave as expected.

class CalculateAreaTest extends PHPUnit\Framework\TestCase
{
    public function testCircleArea()
    {
        $shape = new Circle(3);
        $this->assertEquals(28.27, calculateArea($shape), '', 0.01);
    }
}

Follow these design patterns and best practices to write scalable, maintainable, and reusable PHP code.

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