[Vala] Binding a function that return a structure, not a pointer

[Darren Warner <vala-list dazwin com>]

I'm creating a vapi for libexif (using vala-gen-introspect) which 
includes a function that returns a structure:

typedef struct {ExifLong numerator; ExifLong denominator; }ExifRational;
ExifRational  exif_get_rational  (const unsigned char *b, ExifByteOrder 
order);

If I don't alter ExifRational in my .metadata, the C compiler complains 
about assigning ExifRational to ExifRational * when I try to use the 
function.

If I set ExifRational is_value_type="1", which I believe I should be, 
valac is generating an additional parameter (a pointer to a temporary 
ExifRational) when calling exif_get_rational() - of course the compiler 
complains at this also.

This seems like a newbie question, but I've been unable to find any 
similar examples in the existing bindings, so any help would be appreciated.

Thanks


-Darren