How to eliminate subtype dependency?

Question

In the example below I have written one to_str() function and one set() procedure for every pls_integer subtype. The functions and procedures are almost identical except the type.

How I can eliminate the need to write yet another to_str() and set() for a new subtype without giving up the constraint provided by the subtype ?

Falling back to varchar2 like

procedure set(list in varchar2, prefix in varchar2)

and then calling it as

set(to_str(list), 'foos:')

doesn't sound too great idea and I still need to provide to_str() for each subtype.

I'm open for all kind of different proposals as I'm Oracle newbie and new Oracle features suprise me almost daily.

I'm running 11.2.0.1.0.

create table so1table (
  id number,
  data varchar(20)
);

create or replace package so1 as
  subtype foo_t is pls_integer range 0 .. 4 not null;
  type foolist is table of foo_t;
  procedure set(id_ in number, list in foolist default foolist(1));

  subtype bar_t is pls_integer range 5 .. 10 not null;
  type barlist is table of bar_t;
  procedure set(id_ in number, list in barlist default barlist(5));
end;
/
show errors

create or replace package body so1 as
  /* Do I have always to implement these very similar functions/procedures for
  every single type ? */
  function to_str(list in foolist) return varchar2 as
    str varchar2(32767);
  begin
    for i in list.first .. list.last loop
      str := str || ' ' || list(i);
    end loop;
    return str;
  end;

  function to_str(list in barlist) return varchar2 as
    str varchar2(32767);
  begin
    for i in list.first .. list.last loop
      str := str || ' ' || list(i);
    end loop;
    return str;
  end;

  procedure set(id_ in number, list in foolist default foolist(1)) as
    values_ constant varchar2(32767) := 'foos:' || to_str(list);
  begin
    insert into so1table (id, data) values (id_, values_);
  end;

  procedure set(id_ in number, list in barlist default barlist(5)) as
    values_ constant varchar2(32767) := 'bars:' || to_str(list);
  begin
    insert into so1table (id, data) values (id_, values_);
  end;
end;
/
show errors

begin
  so1.set(1, so1.foolist(0, 3));
  so1.set(2, so1.barlist(5, 7, 10));
end;
/

SQLPLUS> select * from so1table;

        ID DATA
---------- --------------------
         1 foos: 0 3
         2 bars: 5 7 10

Answer 1

create table so1table (
    id number,
    data varchar(20)
);


create or replace type parent_type as object
(
    v_number number,
    --Prefix probably belongs with a list, not an individual value.
    --For simplicity, I'm not adding another level to the objects.
    v_prefix varchar2(10)
) not instantiable not final;
/

create or replace type parentlist as table of parent_type;
/


create or replace type foo_type under parent_type
(
    constructor function foo_type(v_number number) return self as result
);
/

--The data must be stored as a NUMBER, since ADTs don't support
--PL/SQL specific data types.  The type safety is enforced by the
--conversion in the constructor.
create or replace type body foo_type is
    constructor function foo_type(v_number number) return self as result
    as
        subtype foo_subtype is pls_integer range 0 .. 4 not null;
        new_number foo_subtype := v_number;
    begin
        self.v_number := new_number;
        self.v_prefix := 'foos:';
        return;
    end;
end;
/

create or replace type foolist as table of foo_type;
/


create or replace type bar_type under parent_type
(
    constructor function bar_type(v_number number) return self as result
);
/

create or replace type body bar_type is
    constructor function bar_type(v_number number) return self as result
    as
        subtype bar_subtype is pls_integer range 5 .. 10 not null;
        new_number bar_subtype := v_number;
    begin
        self.v_number := new_number;
        self.v_prefix := 'bars:';
        return;
    end;
end;
/

create or replace type barlist as table of bar_type;
/



create or replace package so1 as
    procedure set(id_ in number, list in parentlist);
end;
/

create or replace package body so1 as

    function to_str(list in parentlist) return varchar2 as
        v_value VARCHAR2(32767);
    begin
        for i in list.first .. list.last loop
            if i = 1 then
                v_value := list(i).v_prefix;
            end if;
            v_value := v_value || ' ' || list(i).v_number;
        end loop;

        return v_value;
    end to_str;

    procedure set(id_ in number, list in parentlist) as
        values_ constant varchar2(32767) := to_str(list);
    begin
        insert into so1table (id, data) values (id_, values_);
    end set;
end so1;
/


begin
    --You probably don't want to mix foos and bars, but it is allowed. 
    so1.set(1, parentlist(foo_type(0), foo_type(3)));
    so1.set(2, parentlist(bar_type(5), bar_type(7), bar_type(10)));

    --These would generate "ORA-06502: PL/SQL: numeric or value error"
    --so1.set(1, parentlist(foo_type(5)));
    --so1.set(1, parentlist(bar_type(4)));

end;
/

select * from so1table;