how to get comma seperated values in oracle

CREATE OR REPLACE FUNCTION get_list_text
(
	/*-- comma seperated list of ids --*/
	list_in IN VARCHAR2,
	/*-- table of id to text mapping --*/
	lkup_tbl_in IN VARCHAR2,
	/*-- column containing ids --*/
	key_col_in IN VARCHAR2,
	/*-- column containing text --*/
	desc_col_in IN VARCHAR2
)
return VARCHAR2
AUTHID CURRENT_USER
IS

	TYPE RowCurTyp IS REF CURSOR;
	lkup_desc_cur RowCurTyp;

	v_text_list VARCHAR2(3000);

	v_lkup_key NUMBER;
	v_lkup_desc VARCHAR2(32767);

BEGIN


	-- add commas to front and back of list so that first and last
	-- position are still surrounded by commas for replace search
	v_text_list := ','||list_in||',';

	OPEN lkup_desc_cur
	FOR '
		select '||key_col_in||' lkup_key, '||desc_col_in||' lkup_desc
		from '||lkup_tbl_in||'
		where '||key_col_in||' in ('||list_in||')';

	LOOP
      	FETCH lkup_desc_cur INTO v_lkup_key, v_lkup_desc;
		EXIT WHEN lkup_desc_cur%notfound;

		v_text_list := replace(v_text_list, 
                                             ','||v_lkup_key||',',
                                             ','|| v_lkup_desc||',');
				
	END LOOP;

	-- remove commas added as first step
	v_text_list := trim(BOTH ',' FROM v_text_list);

	CLOSE lkup_desc_cur;

	RETURN v_text_list;

END get_list_text;
/