try
{
        $guid = new Guid('1231212311231233211233212312345');
        var_dump($guid);
}
catch(SystemException $e)
{
    print $e;
}

/*
Exception    ObjectHandlerException
Error        0x00010601
Level        3
Message      Can not create object.
Mem          1.264892578125
Thrown in
    Line     00001293
    File     ../types.php

Exception    DatatypeExpectedException
Error        0x00030412
Level        2
Message      Guid expected.
Mem          1.264892578125
Thrown in
    Line     00001268
    File     ../types.php

Exception    ArgumentExpectedException
Error        0x00020403
Level        1
Message      String is to short.
Mem          1.264892578125
Thrown in
    Line     00001256
    File     ../types.php