Re: __toString() must return a string value

On Sun, 2009-02-22 at 09:19 +0100, Piotr Pokora wrote: > What might return NULL zval? > > PHP_FUNCTION(date_format) > { > [...] > RETURN_STRING(date_format(format, format_len, dateobj->time, > dateobj->time->is_localtime), 0); > } > > Can you give me a pointer where this method(function) returns NULL zval > so I should really worry about in derived class? I didn't check the code, before, but go up 3 or 4 lines and you read RETURN_FALSE in case arguement parsing fails - usually we return null in that case ... > Of course, you are > right, to avoid future segfaults when API change I should return zval. ... but that's the point: You should not rely on the types. > But, I started this thread to talk about this particular case. That was also meant as general hint .. > Should it looks like this? > > MAKE_STD_ZVAL(return_value); > Z_TYPE_P(return_value) = IS_STRING; > zend_call_method_with_1_params(&zend_object, > Z_OBJCE_P(zend_object), NULL, "format", &return_value, fmt); If you debug this you will see that, after calling zend_call_method, return_value points to a string zval having the formatted date, but it will point to a different place than where the engine expects your return value. Using simple printf-"debugging": php_printf("before calling zend_call_method: %x\n", return_value); zend_call_method_with_1_params(&zend_object, Z_OBJCE_P(zend_object), NULL, "format", &return_value, fmt); php_printf("after calling zend_call_method: %x\n", return_value); You will see that return_value is different there, whereas with php_printf("before setting retval: %x\n", return_value); RETVAL_STRING("a new return value", 1); php_printf("after setting retval: %x\n", return_value); the address will be the same. And no the problem is not within Zend/PHP APIs but C pointer stuff. johannes