Identifying and resolving PHP code smells

Yes, PHP code smells are signs of bad practices or design issues in your code. It's critical to identify and resolve these smells to keep your codebase healthy and maintainable. Common PHP code smells include: Duplicate code Long methods/functions Global variables Overcoupling Magic methods Identifying code smells can be done using static code analysis tools such as PHPStan or Psalm. Solving code smells can be achieved by extracting methods, using design patterns, using namespaces, following coding style guides, and doing continuous integration. By applying these principles, you can improve code quality and maintainability.

PHP Code Smell Identification and Resolution

PHP code smells are signs of bad practices or design issues in your code. Identifying and resolving these smells is critical to keeping your codebase healthy and maintainable.

Common PHP code smells

• Duplicate code: Code segments are repeated in multiple places.
• Long methods/functions: Methods or functions contain too much code and are difficult to understand and maintain.
• Global variables: Code relies on global variables that are outside its scope.
• Overcoupling: Classes and methods are highly dependent on each other, making it difficult to modify and test.
• Magic methods: Abuse of magic methods (such as __construct()), leading to unpredictable behavior.

Identifying Code Smells

You can use static code analysis tools such as PHPStan or Psalm to identify code smells. These tools inspect the code and highlight potential issues.

Resolving code smells

• Extraction method: Extract code blocks in long methods into separate methods.
• Use design patterns: Apply design patterns to reduce coupling and increase reusability.
• Use namespaces: Use namespaces to avoid naming conflicts and global variable dependencies.
• Follow the coding style guide: Follow a unified coding style to improve readability and consistency.
• Perform continuous integration: Use automated testing and continuous integration to quickly identify and fix code issues.

Practical Case

Consider the following code smell example:

// 重复代码
function calculateDiscount(Order $order) {
  if ($order->type == 'wholesale') {
    return $order->total * 0.1;
  } elseif ($order->type == 'retail') {
    return $order->total * 0.05;
  }
}

function calculateShippingCost(Order $order) {
  if ($order->type == 'wholesale') {
    return $order->weight * 0.5;
  } elseif ($order->type == 'retail') {
    return $order->weight * 1;
  }
}

This code smell can be extracted into a new class as shown below :

class OrderCalculator {
  public function calculateDiscount(Order $order): float {
    switch ($order->type) {
      case 'wholesale':
        return $order->total * 0.1;
      case 'retail':
        return $order->total * 0.05;
    }
  }

  public function calculateShippingCost(Order $order): float {
    switch ($order->type) {
      case 'wholesale':
        return $order->weight * 0.5;
      case 'retail':
        return $order->weight * 1;
    }
  }
}

By applying these principles, smells in PHP code can be identified and resolved, thereby improving code quality and maintainability.

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