Re: __toString() must return a string value

Hi, On Sat, 2009-02-21 at 20:02 +0100, Piotr Pokora wrote: > >> zend_call_method_with_1_params(&zend_object, > >> Z_OBJCE_P(zend_object), NULL, "format", &return_value, fmt); > > > > here you are passing the address of your local variable "return_value" > > so zend_call_method will change the pointer. It's basically like doing > > > > return_value = 23; > > return_value is predefined variable of type zval, so what it's the > difference? it is no zval but a pointer to a zval (zval* for short) > Looks like it's common practice to implement code like: > > object_init_ex(return_value, ce); > array_init(return_value); > > Isn't it? That code is passing the pointer so these unctions can work on the zval the pointer is pointing to. > > [...] > >> zval *strv = NULL; > >> zend_call_method_with_1_params(&zend_object, Z_OBJCE_P(zend_object), > >> NULL, "format", &strv, fmt); > >> RETURN_STRING(Z_STRVAL_P(strv), 0); > > > > When doing this you should check they type. You might also use > > RETURN_ZVAL() if you don't care for the type. > > Why? Isn't it DateTime::format responsible to set string? It might return a NULL-zval in case it has problems passing the parameter or in case of another error. > Besides... RETURN_STRING will copy strv to return_value. It will interpret the value as sring value and copy it, in case format returns a NUL zval this might be a andom amount of random memory with a little luck you get no weird data but the system emits a sementation ault to tell you it's wrong. > And, am I really responsible to set type of zval when passing it as > in/out function argument? Yes. > Again. Is there common convention to (not) use return_value? use return_value to find the zval structure, not having it point somewhere else. Probably you should fetch a C book and e-read the chapter about pointers. johnnes