Example 8-19 Aliasing from Passing Global Variable with NOCOPY Hint

DECLARE
   TYPE Definition IS RECORD (
      word    VARCHAR2(20),
      meaning VARCHAR2(200));
   TYPE Dictionary IS VARRAY(2000) OF Definition;
   lexicon Dictionary := Dictionary();
   PROCEDURE add_entry (word_list IN OUT NOCOPY Dictionary) IS
   BEGIN
     word_list(1).word := 'aardvark';
     lexicon(1).word := 'aardwolf';
   END;
BEGIN
   lexicon.EXTEND;
   add_entry(lexicon);
   DBMS_OUTPUT.PUT_LINE(lexicon(1).word);
END;
/

The program prints aardwolf if the compiler obeys the NOCOPY hint. The assignment to WORD_LIST is done immediately through a pointer, then is overwritten by the assignment to LEXICON.

The program prints aardvark if the NOCOPY hint is omitted, or if the compiler does not obey the hint. The assignment to WORD_LIST uses an internal copy of the varray, which is copied back to the actual parameter (overwriting the contents of LEXICON) when the procedure ends.