Re: Schroedinger Objects

Yep I think that's a good point. Checking for cast is the right thing IMO. At 02:45 PM 8/24/2005, Rasmus Lerdorf wrote:

As per bug #34199 and as Rob points out, if($obj) and if(!$obj) are handled by different opcodes and these two opcodes are inconsistent in whether they call an object's cast_object handler. if($obj) results in a ZEND_JMPZ_SPEC_CV_HANDLER which calls i_zend_is_true() which always return true for objects, no matter what (ignore compatibility mode here) because of this code in zend_execute.h:

        case IS_OBJECT:
            if(IS_ZEND_STD_OBJECT(*op)) {
                TSRMLS_FETCH();
                if(EG(ze1_compatibility_mode)) {
                    result = (zend_hash_num_elements(Z_OBJPROP_P(op))?1:0);
                } else {
                    result = 1;
                }
            } else {
                result = 1;
            }
            break;

if(!$obj) results in a which calls convert_to_boolean() which in turn calls convert_object_to_type() which has: if (Z_OBJ_HT_P(op)->cast_object) {

    if (Z_OBJ_HT_P(op)->cast_object(op, op, ctype, 1 TSRMLS_CC) ==

SUCCESS) {

         op->type = ctype;

    }

This means that any object which actually implements a cast_object handler that returns false under some condition will be broken. The simple example is: $a = simplexml_load_string('<a></a>'); if($a && !$a) echo "BUG!"; I think we need to fix i_zend_is_true's IS_OBJECT case to check to see if the object has a cast_object handler and call it or just call convert_to_boolean() there. Or we need to clean this up and not have such different codepaths for these two cases. -Rasmus -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php