How to catch an invalid array index offset as a native exception in PHP (RAII supported)

test_undefined_offset_exception.php

<?php

/**
 * this class shows how to override default PHP handler to catch undefined index errors
 * and throw it as native exceptions, much more convenient way to work with object
 * oriented programs.
 *
 * @author Moisés Maciá <[email protected]>
 * @see http://codeup.net
 */

class A {
  public function __construct()
  {
    echo "CTOR\n";
    // override default error handler with our own closure that will detect
    // undefined offsets in arrays
    //
    // Error handler should not be a closure
    // if we want to expect RAII, 
    // i.e., to call the dtor automatically at the end of a scope.
    // A closure defined in a regular member function
    // captures '$this' reference.
    // The captured $this prevents from calling the dtor
    // becasue the life scope of the captured $this reference
    // is the same as the closure.
    // This is why we define the error handler as a static function.
    set_error_handler('A::error_handler');
  }

  public function __destruct()
  {
    // very important, restore the previous error handler when finish
    restore_error_handler();
    echo "DTOR\n";
  }
  
  public static function error_handler($errno, $errstr, $errfile, $errline)
  {
      // we are only interested in 'undefined index/offset' errors
      if (preg_match("/^Undefined offset|index/", $errstr)) {
        throw new OutOfRangeException($errstr);
      }

      return FALSE; // If the function returns FALSE then the normal error handler continues.
  }
}

function exception_needed_function()
{
  // exception available only in this scope
  $IndexErrorAsException = new A();
  
  $matrix = [];
  
  try {
    return $matrix[0][0];
  }
  catch (OutOfRangeException $e) {
    echo "OutOfRangeException caught\n";
  }
}

function exception_unneeded_function()
{
  $matrix = [];
  return $matrix[0][0];
}

exception_needed_function();
echo "---------------------------\n";
exception_uneeded_function();
echo "End of scrypt\n";