SQL> select  banner
  2    from  v$version
  3  /

BANNER
--------------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production
PL/SQL Release 12.2.0.1.0 - Production
CORE    12.2.0.1.0      Production
TNS for 64-bit Windows: Version 12.2.0.1.0 - Production
NLSRTL Version 12.2.0.1.0 - Production

SQL> CREATE OR REPLACE
  2    TYPE  natural_vector_type
  3      AUTHID CURRENT_USER
  4      AS OBJECT(
  5                fetch_more varchar2(1),
  6                tmt        SYS.ANYTYPE,
  7                num_cols   INTEGER,
  8                STATIC FUNCTION ODCITableStart(
  9                                               sctx     IN OUT natural_vector_type,
 10                                               num_cols IN     INTEGER
 11                                              ) RETURN PLS_INTEGER,
 12                STATIC FUNCTION ODCITablePrepare(
 13                                                 sctx     OUT natural_vector_type,
 14                                                 tf_info  IN  SYS.ODCITabFuncInfo,
 15                                                 num_cols IN  INTEGER
 16                                                ) RETURN PLS_INTEGER,
 17                MEMBER FUNCTION ODCITableFetch(
 18                                               self   IN OUT natural_vector_type,
 19                                               nrows  IN     NUMBER,
 20                                               objSet OUT    SYS.ANYDATASET
 21                                              ) RETURN PLS_INTEGER,
 22                MEMBER FUNCTION ODCITableClose(
 23                                               self IN natural_vector_type
 24                                              ) RETURN PLS_INTEGER,
 25                STATIC FUNCTION ODCITableDescribe(
 26                                                  rtype    OUT SYS.ANYTYPE,
 27                                                  num_cols IN  INTEGER
 28                                                 ) RETURN PLS_INTEGER
 29               )
 30  /

Type created.

SQL> CREATE OR REPLACE
  2    TYPE BODY natural_vector_type
  3      IS
  4        STATIC FUNCTION ODCITableStart(
  5                                       sctx     IN OUT natural_vector_type,
  6                                       num_cols IN     INTEGER
  7                                      ) RETURN PLS_INTEGER
  8          IS
  9          BEGIN
 10              RETURN ODCICONST.SUCCESS;
 11        END;
 12        STATIC FUNCTION ODCITablePrepare(
 13                                         sctx     OUT natural_vector_type,
 14                                         tf_info  IN  SYS.ODCITabFuncInfo,
 15                                         num_cols IN  INTEGER
 16                                        ) RETURN PLS_INTEGER
 17          IS    
 18              rtn number ;
 19              prec     PLS_INTEGER;
 20              scale    PLS_INTEGER;
 21              len      PLS_INTEGER;
 22              csid     PLS_INTEGER;
 23              csfrm    PLS_INTEGER;
 24              elem_typ SYS.ANYTYPE;    
 25              aname    VARCHAR2(30) ;
 26          BEGIN
 27              rtn:=tf_info.RetType.GetAttreleminfo(
 28                                                   1,
 29                                                   prec,
 30                                                   scale,
 31                                                   len,
 32                                                   csid,
 33                                                   csfrm,
 34                                                   elem_typ,
 35                                                   aname
 36                                                  );
 37              sctx:= natural_vector_type('Y',elem_typ,num_cols);
 38              RETURN ODCICONST.SUCCESS;    
 39        END;
 40        MEMBER FUNCTION ODCITableFetch(
 41                                       self   IN OUT natural_vector_type,
 42                                       nrows  IN     NUMBER,
 43                                       objSet OUT    SYS.ANYDATASET
 44                                     ) RETURN PLS_INTEGER
 45          IS
 46              elem_typ SYS.ANYTYPE;
 47          BEGIN
 48              SYS.ANYDATASET.BeginCreate(
 49                                         SYS.DBMS_TYPES.TYPECODE_OBJECT,
 50                                         tmt,
 51                                         objSet
 52                                        );
 53              IF fetch_more = 'Y'
 54                THEN
 55                  fetch_more := 'N';
 56                  objSet.Addinstance;          
 57                  objSet.PieceWise;
 58                  FOR i IN 1..self.num_cols LOOP  
 59                    objSet.SetNumber(
 60                                     i,
 61                                     CASE
 62                                       WHEN i = self.num_cols
 63                                         THEN
 64                                           TRUE
 65                                         ELSE
 66                                           FALSE
 67                                     END
 68                                    );              
 69                  END LOOP;           
 70                  objSet.Endcreate;            
 71                ELSE
 72                  objSet:=null;
 73              END IF;
 74              RETURN ODCICONST.SUCCESS;
 75        END;
 76        MEMBER FUNCTION ODCITableClose(
 77                                       self IN natural_vector_type
 78                                      ) RETURN PLS_INTEGER
 79          IS
 80          BEGIN
 81              RETURN ODCICONST.SUCCESS;
 82        END;
 83        STATIC FUNCTION ODCITableDescribe(
 84                                          rtype    OUT SYS.ANYTYPE,
 85                                          num_cols IN  INTEGER
 86                                         ) RETURN PLS_INTEGER
 87          IS
 88              mt SYS.ANYTYPE;
 89              tmt SYS.ANYTYPE;
 90          BEGIN
 91              SYS.ANYTYPE.BeginCreate(
 92                                      SYS.DBMS_TYPES.TYPECODE_OBJECT,
 93                                      mt
 94                                     );    
 95              FOR i IN 1..num_cols LOOP
 96                mt.AddAttr(
 97                           'C' || i,
 98                           SYS.DBMS_TYPES.TYPECODE_NUMBER,
 99                           NULL,
100                           NULL,
101                           NULL,
102                           NULL,
103                           NULL
104                          );
105              END LOOP;  
106              mt.EndCreate;
107              SYS.ANYTYPE.BeginCreate(
108                                      SYS.DBMS_TYPES.TYPECODE_NAMEDCOLLECTION,
109                                      tmt
110                                     );    
111              tmt.SetInfo(
112                          NULL,
113                          NULL,
114                          NULL,
115                          NULL,
116                          NULL,
117                          mt,
118                          DBMS_TYPES.TYPECODE_OBJECT,
119                          0
120                         );
121              tmt.EndCreate;
122              rtype:=tmt;
123              RETURN ODCICONST.SUCCESS;
124        END;
125  END;
126  /

Type body created.

SQL> CREATE OR REPLACE
  2    FUNCTION natural_vector(num_cols INTEGER) RETURN ANYDATASET
  3      PIPELINED
  4        USING natural_vector_type;
  5  /

Function created.

SQL> SELECT  *
  2    FROM  TABLE(
  3                natural_vector(5)
  4               )
  5  /

        C1         C2         C3         C4         C5
---------- ---------- ---------- ---------- ----------
         1          2          3          4          5

SQL> VARIABLE n NUMBER
SQL> exec :n := 5;

PL/SQL procedure successfully completed.

SQL> SELECT  *
  2    FROM  TABLE(
  3                natural_vector(:n)
  4               )
  5  /
SELECT  *
*
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error
ORA-06512: at "SCOTT.NATURAL_VECTOR_TYPE", line 104
ORA-06512: at line 4


SQL>