Detailed introduction to exception handling code examples in PHP7

Preface

Among the changes in PHP7, those that have a greater impact include Exception handling.

Overview

More exceptions are handled directly through PHP. Different from the previous PHP5, more exceptions are thrown through Error exceptions.

As a normal extension, Error exceptions will continue to pop up until the corresponding catch block is matched. If no match is made, the set set_exception_handler() will be triggered to perform processing. If there is no default exception handler, the exception will be converted to a fatal error and will be treated like a traditional The error is handled.

Since Error does not inherit exceptions in the error hierarchy, code like this catch (Exception $e) { ... } will not catch the corresponding exception in PHP5. We can use the code catch (Error $e) { ... } or set_exception_handler() to handle Error.

Wrong hierarchy

• Throwable
  

• ##….

• ArithmeticError Arithmetic Error

  
  

• AssertionError Statement Error

• ParseError Parse Error

• TypeError Type error

• pisionByZeroError Divisor by 0 error

• Error Error

  
  

• Exception Exception

  
  

PHP RFC

Throwable Interface

function add(int $left, int $right) {
    return $left + $right;
}try {    echo add('left', 'right');
} catch (Exception $e) {    // Handle exception} catch (Error $e) { // Clearly a different type of object
    // Log error and end gracefully
    var_dump($e);
}

Here, there is no server 500 error. The reason is that the Error in PHP7 intercepts it and does not bubble up in the server.

object(TypeError)#1 (7) {
  ["message":protected]=>  
  string(139) "Argument 1 passed to add() must be of the type integer, string given, called in /Applications/mamp/apache2/htdocs/curl/error.php on line 14"
  ["string":"Error":private]=>  string(0) ""
  ["code":protected]=>  int(0)
  ["file":protected]=>  string(48) "/Applications/mamp/apache2/htdocs/curl/error.php"
  ["line":protected]=>  int(9)
  ["trace":"Error":private]=>
  array(1) {
    [0]=>
    array(4) {
      ["file"]=>      string(48) "/Applications/mamp/apache2/htdocs/curl/error.php"
      ["line"]=>      int(14)
      ["function"]=>      string(3) "add"
      ["args"]=>
      array(2) {
        [0]=>        string(4) "left"
        [1]=>        string(5) "right"
      }
    }
  }
  ["previous":"Error":private]=>
  NULL
}

So we can record them through logs.

Exceptions in the engine (for PHP 7)

function call_method($obj) {
    $obj->method();
}try {
    call_method(null);
     // oops!
     } 
     catch (EngineException $e) {    
    echo "Exception: {$e->getMessage()}\n";
}//其实上面的例子我在运行过程中，并没有被EngineException捕获异常,经过测试，也是通过Error进行的错误的拦截

If the exception is not caught, PHP will continue to throw the same fatal error as it currently does.

Reclassify E_STRICT notices

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