[Vala] Problem converting c to vala/genie

[Nicolas <c r n a wanadoo fr>]

Hello,

I'm trying to use a c library in genie and i have a question about 
converting code.
This is the c code who makes me crazy !

The struct:
typedef struct _Widget_Data Widget_Data;
struct _Widget_Data
{
   Object *myboject
};

Now in the function:
Widget_Data *wd;
wd = ELM_NEW(Widget_Data); <-- this is the problem

The ELM_NEW is declared like this in the header file:
#define ELM_NEW(t) calloc(1, sizeof(t))

How can i convert this on genie (or vala), at least it is possible ?
Thanks you in advance,
Nicolas.