PHP 尝试，捕获优先级和继承

Question

我想知道一些关于 PHP 的 try , catch声明。

让我们考虑以下示例。

abstract class ExceptionA extends Exception
{}

class ExceptionB extends ExceptionA
{}

class ExceptionTest
{
    public function example()
    {
        try {
            throw new ExceptionB();
        } catch ( ExceptionB $e ) {
            echo 'ExceptionB was caught';
        } catch ( ExceptionA $e ) {
            echo 'ExceptionA was caught';
        } catch ( Exception $e ) {
            echo 'Exception was caught';
        }
    }
}

全部 catch语句匹配异常。其中第一个 ( ExceptionB ) 是最接近的匹配项。

请问catch的顺序哪些言论会受到影响呢？

Answer 1

每 the manual :

When an exception is thrown, code following the statement will not be executed, and PHP will attempt to find the first matching catch block.

您可以轻松确认:

捕捉 ExceptionB第一的:

class ExceptionTest
{
    public function example()
    {
        try {
            throw new ExceptionB();
        } catch (ExceptionB $e) {
            echo 'ExceptionB was caught';
        } catch (ExceptionA $e) {
            echo 'ExceptionA was caught';
        } catch (Exception $e) {
            echo 'Exception was caught';
        }
    }
}

(new ExceptionTest())->example();  // Exception B was caught

演示:https://3v4l.org/htgEg

捕捉 ExceptionA首先和ExceptionB后:

class ExceptionTest
{
    public function example()
    {
        try {
            throw new ExceptionB();
        } catch (ExceptionA $e) {
            echo 'ExceptionA was caught';
        } catch (ExceptionB $e) {
            echo 'ExceptionB was caught';
        } catch (Exception $e) {
            echo 'Exception was caught';
        }
    }
}

(new ExceptionTest())->example();  // Exception A was caught

演示:https://3v4l.org/J7Xul