The ITMVDesc class
The ITMVDesc structure is not an operation class, but a descriptor that holds the instance information necessary to create a value object. The ITMVDesc structure is passed to the factory constructor function when an object of a given server type is retrieved from the server and loaded into the application.
This structure contains the following individual members.
| Member | Description |
|---|---|
| long vf_datalength | Data length in bytes, pointed to by the member data pointer vf_data. |
| ITConnection *vf_connection | Pointer to the connection object. |
| int vf_libmivaluetype | Return value of the call to a DataBlade® API function call [mi_value(...)]; see the Informix® DataBlade API Programmer's Guide for complete documentation of DataBlade API function calls. |
| char *vf_data | Points to the datum underlying the value object. For example, for the server type lvarchar, vf_data points to the MI_LVARCHAR structure. |
| ITypeInfo *vf_origtypeinfo | Points to the ITTypeInfo object for the value object. |
| ITEssential *vf_outerunknown | Points to the IUnknown interface of the object
that is the controlling unknown for the object delegation/aggregation
process.
Value is The vf_outerunknown member is assigned the value of the inner unknown of the object when ITMVDesc * is passed to the entry point function MakeValue(ITMVDesc *), which is implemented by the value object developer. |
| ITPreserveData *vf_preservedata | Can point to the ITPreserveData interface of an
object that manages the datum memory.
For a detailed description of the vf_preservedata member and its use, see Value objects and connection events. |