Creating derived topic types using Dynamic Data

Hello,

in order to do that you have to use DDS_TypeCodeFactory_create_value_tc that gets the base class as a parameter. 

First thing to do is to create the type code for the type:

DDS_TypeCode *MyType_create() {
    struct DDS_TypeCodeFactory * factory = NULL;
    struct DDS_TypeCode * shapeTc = NULL;   /* Typecode for 'base class Shape'     */
    struct DDS_TypeCode * squareTc = NULL;     /* Typecode for Square      */
    DDS_ExceptionCode_t ex;
    struct DDS_StructMemberSeq memberSeq = DDS_SEQUENCE_INITIALIZER;
    struct DDS_ValueMemberSeq valueMemberSeq = DDS_SEQUENCE_INITIALIZER;
    
    factory = DDS_TypeCodeFactory_get_instance();
    if (factory == NULL) {
        fprintf(stderr, "! Unable to get type code factory singleton\n");
        goto done;
    }
    
    shapeTc = DDS_TypeCodeFactory_create_struct_tc(
                                                    factory,
                                                    "Shape",
                                                    &memberSeq,
                                                    &ex);
    if (ex != DDS_NO_EXCEPTION_CODE) {
        fprintf(stderr, "! Unable to create struct typecode, error=%d\n", ex);
        goto done;
    }
    
    DDS_TypeCode_add_member(shapeTc,
                            "area",
                            DDS_MEMBER_ID_INVALID,
                            DDS_TypeCodeFactory_get_primitive_tc(factory,
                                                                 DDS_TK_FLOAT),
                            DDS_TYPECODE_NONKEY_REQUIRED_MEMBER,
                            &ex);
    if (ex != DDS_NO_EXCEPTION_CODE) {
        fprintf(stderr, "! Unable to add member to struct typecode, error=%d\n",
                ex);
        goto done;
    }
    
    squareTc = DDS_TypeCodeFactory_create_value_tc(
                                                   factory,
                                                   "Square",
 													DDS_VM_NONE,
												shapeTc,
                                                   &valueMemberSeq,
                                                   &ex);
    if (ex != DDS_NO_EXCEPTION_CODE) {
        fprintf(stderr, "! Unable to create struct typecode, error=%d\n", ex);
        goto done;
    }
    
    DDS_TypeCode_add_member(squareTc,
                            "side_length",
                            1,
                            DDS_TypeCodeFactory_get_primitive_tc(factory,
                                                                 DDS_TK_FLOAT),
                            DDS_TYPECODE_NONKEY_REQUIRED_MEMBER,
                            &ex);
    if (ex != DDS_NO_EXCEPTION_CODE) {
        fprintf(stderr, "! Unable to add member to struct typecode, error=%d\n",
                ex);
        goto done;
    }
    
    return squareTc;
    
done:
    
    if (shapeTc != NULL) {
        DDS_TypeCodeFactory_delete_tc(factory, shapeTc, &ex);
    }
    if (squareTc != NULL) {
        DDS_TypeCodeFactory_delete_tc(factory, squareTc, &ex);
    }
    return NULL;
}

To verify that the type is what you want you can call the print_IDL function:

DDS_TypeCode *squareTc = MyType_create(); DDS_TypeCode_print_IDL(squareTc,4,NULL);

You shold get:

            struct Square : Shape {
               public float side_length;
               //@ID 1
            }; //@Extensibility EXTENSIBLE_EXTENSIBILITY

Now you can proceed as usual registering the type and creating the topic

    /* Create the Dynamic data type support object
     */
    typeSupport = DDS_DynamicDataTypeSupport_new(squareTc, 
                        &props);
    if (typeSupport == NULL) {
        fprintf(stderr, "! Unable to create dynamic data type support\n");
        goto exitFn;
    }

    /* Register type before creating topic */
    rc = DDS_DynamicDataTypeSupport_register_type(typeSupport, 
                        participant, 
                        typeName);
    if (rc != DDS_RETCODE_OK) {
        fprintf(stderr,"! Unable to register dynamic type\n");
        goto exitFn;
    }

Let me know if this answers your question.

Best,
   Gianpiero