How to customize PHP exception class?

How to customize PHP exception class? Extend the built-in Exception class to create custom exception classes. Pass the message, error code, and previous exception (optional) in the constructor. Create custom exceptions for specific situations, providing more detailed error messages.

How to customize PHP exception class?

The exception class is a powerful mechanism for handling errors and exceptions in PHP. Custom exception classes allow you to create application-specific exceptions, providing more informative and actionable error messages.

Create a custom exception class

The custom exception class extends PHP’s built-in Exception class. The following is how to create a custom exception class:

class MyException extends Exception
{
    public function __construct($message, $code = 0, Exception $previous = null)
    {
        // 调用父类的构造函数传递消息、错误码和前一个异常（可选）
        parent::__construct($message, $code, $previous);
    }
}

Practical case

Let us create a custom exception class to handle file opening failure:

class FileOpenException extends Exception
{
    public function __construct($message, $code = 0, Exception $previous = null)
    {
        parent::__construct($message, $code, $previous);
    }
}

try {
    // 尝试打开一个不存在的文件
    $handle = fopen('non-existent-file.txt', 'r');
} catch (FileOpenException $e) {
    // 捕获并处理自定义异常
    echo '无法打开文件：' . $e->getMessage();
}

Custom Exception Messages

Custom exception classes allow you to define specific exception messages. In the following example, FileOpenException will display a more detailed error message:

class FileOpenException extends Exception
{
    public function __construct($filename, $code = 0, Exception $previous = null)
    {
        $message = "无法打开文件 $filename。";
        parent::__construct($message, $code, $previous);
    }
}

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