NULL is OK, both for passing and for returning.
This parameter is a 'user_data', for callbacks; many bindings can pass NULL here.
Generics and defining elements of containers and arrays.
NULL may be passed as the value in, out, in-out; or as a return value.
Parameter for returning results. Default is transfer full.
The callback is valid only during the call to the method.
The callback is valid until the GDestroyNotify argument is called.
Alias for transfer none, used for objects with floating refs.
Free data after the code is done.
Don't free data after the code is done.
Override the parsed C type with given type.