OMobj_id

Definition

AVS/Express assigns each object a unique id.

In a C function, the id's type is OMobj_id.

For example, the following V code defines group object grp1 and two subobjects, a and b:

group grp1 {
int a;
int b;
};

A C program can obtain the object ids of grp1, a, and b. Assume that grp1's parent id is parent_id:

OMobj_id parent_id, grp1_id, a_id, b_id;
...
grp1_id = OMfind_subobj(parent_id, OMstr_to_name("grp1"),
OM_OBJ_RW);
a_id = OMfind_subobj(grp1_id, OMstr_to_name("a"),
OM_OBJ_RW);
b_id = OMfind_subobj(grp1_id, OMstr_to_name("b"),
OM_OBJ_RW);

OMobj_id is a structure

OMobj_id is a two-value structure defined in the header file <avs/om.h> as follows:

typedef struct _OMobj_id {
OMobj_id_type  obj_id; /* Pointer within a process. */
OMproc_id  proc_id; /* Process id. */
} OMobj_id;

Initializing a OMobj_id

You generally can ignore the fact that OMobj_id is a structure. But be aware that on some compilers, you cannot initialize a OMobj_id in its declaration:

OMobj_id id = OMnull_obj;  /* Error on some compilers. */

Instead, do the following:

OMobj_id id;
id = OMnull_obj;

Comparing ids

To compare object ids, use the routine OMequal_objs:

if (OMequal_objs(obj_id1, obj_id2))
...

Determining whether an id is null

To determine whether an object id is null, use the routine OMis_null_obj:

if (OMis_null_obj(obj_id))
...

Predefined object ids

The following are variables of type OMobj_id. They are provided by the Object Manager, in <avs/om.h>, and initialized at system start-up.