PL/SQL - Avoid Compiler warning: "value assigned, never used"

Question

As you've probably gathered, the code below isn't real - but it highlights my point.

PROCEDURE Do_Some_Dynamic_Stuff (
    sql_  IN VARCHAR2 )
IS
    cur_ INTEGER := Dbms_Sql.Open_Cursor;
    res_ NUMBER;
BEGIN
    Dbms_Sql.Parse (cur_, sql_, dbms_sql.native);
    res_ := Dbms_Sql.Execute (cur_);
    -- ...
    -- > use cursor cur_ in this code to achieve "stuff"
    -- > value `res_` never required by the program
    -- > end program successfully without errors
    -- ...
END Do_Some_Dynamic_Stuff;

When compiled, the above procedure will produce a compiler warning: Hint: Value assigned to 'res_' never used.

I know what the warning means, and it makes sense to have the issue highlighted because it can help tidy up old code when variables defined in the DECLARE (or IS) block become redundant/unused.

I have seen similar questions asked on SO, but the answers suggest toning down the Warning levels in Oracle. The problem is that:

1. I don't always have access to do this
2. I don't want to switch off the warnings - as stated, I normally like to see the message since it helps maintain clean code when a genuine variable is declared and never used

The point is that in the above scenario, the res_ variable is necessary to allow the code to compile, but is unnecessary in the context of the PROCEDURE. I just want a way to suppress the message in this instance of the warning

Of course, one way to work around the problem is to add a pointless line of code such as:

Dbms_Output.Put_Line ('avoid compiler warning: ' || res_);

But that's hardly a very eloquent solution, and anyway it clogs up your debug output etc. etc. So I'm just wondering if someone out there may have a pretty solution to this little bug bear.

Answer 1

If you are using pl/sql developer, you might want to try this (excerpt from PL/SQL Developer 12.0 User’s Guide):

To suppress a warning you can add a -- Ignore comment after the line that produces the hint. This works both for Oracle compilation warnings described in this chapter and for PL/SQL Developer hints as described in chapter 20.9. You can add additional text after -- Ignore to describe the situation

Just note that these comments are not portable to other IDE's.