New error handling mechanism in PHP8.0: throwable interface

In PHP8.0, a very important update is the improvement of the error handling mechanism, which introduces a new interface-throwable. This interface includes two exception types, Error and Exception, so that developers do not need to distinguish between errors and exceptions that comply with catchable exception specifications. Below, we will introduce the throwable interface in detail.

1. What is throwable?

throwable is a new interface introduced in PHP8.0, including two exception types: Error and Exception. Different from the previous error handling mechanism, in PHP8.0, we can use try-catch block to handle Error type exceptions, which provides us with a more flexible and convenient way to handle errors in the program.

2. Characteristics of throwable

The characteristics of throwable mainly include the following points:

(1) Contains two exception types: Error and Exception;

(2) Error type exceptions can also be captured and handled using try-catch blocks;

(3) Error and Exception type exceptions can be captured using interface type hints and type declarations;

(4) There is no need to explicitly declare when using RuntimeException to throw an exception, which is different from before PHP7.0.

3. How to use throwable

In PHP8.0, we can use the try-catch block to handle exceptions of type Error:

try {
    $a = 1 / 0;
} catch (Throwable $t) {
    echo 'Error: ' . $t->getMessage();
}

The above code , we try to divide the integer 1 by 0, which throws an exception of type Error. We use the try-catch block to catch and handle the exception and output the exception information.

We can also use Type-Hinting in conjunction with the throwable interface to specify the type of exception to be caught:

function test(): int {
    try {
        $a = 1 / 0;
    } catch (Throwable $t) {
        return 0;
    }
    return $a;
}

In the above code, we define a test function that will return an integer. In the function, we try to divide the integer 1 by 0 and use a try-catch block to catch the exception of type Error. If an exception is caught, 0 is returned, otherwise the calculated integer is returned.

If you do not use a try-catch block to catch exceptions of type Error, throwing an exception of type Error directly will result in a fatal error.

4. Use of throwable interface in certain scenarios

When we need to customize some exception types in the program, we can also use the throwable interface to achieve:

class MyException implements Throwable{
    //code here
}

try {
    throw new MyException('This is a custom exception');
} catch (Throwable $t) {
    echo 'Error: ' . $t->getMessage();
}

In the above code, we defined a custom exception type named MyException and implemented the Throwable interface. Inside the try block, we throw an exception of type MyException and use the catch block to catch the exception.

5. Summary

The throwable interface is a very important update in PHP8.0, providing more flexibility and convenience in the error handling mechanism. Through the throwable interface, we can handle Error type exceptions in the program, and we can use Type-Hinting to specify the exception type to be caught. In some cases, we can also use the throwable interface to customize some exception types.

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