Re: Constants (was: *varsize array as procedure parameter)

[Ken Sims <mdrg5003@xxxxxxxxx>]

Hi David -

> If a const is just a pointer to a variable that isn't allowed to be
> changed ... is there any reason I couldn't take the address of that
> pointer, assign it to another (non-const) variable, and change the
> const's value that way?

The compiler won't let you do this, just in case a temporary field is not 
needed and a pointer to a regular program variable is passed.

If you try to use the %addr other than for testing if it is *null, you get 
a compiler error:

 Msg id  Sv   Statement    Message 
text
*RNF7586 20                The address of a constant value is used incorrectly.

Message . . . . :   The address of a constant value is used incorrectly.
Cause . . . . . :   The address of a constant value cannot be assigned or
  passed as a parameter. The expression is dropped.
Recovery  . . . :   Correct the value being assigned or passed as a parameter.
  Compile again.

In older releases, the compiler wouldn't even let you test against *null, 
so you could define a parameter as CONST OPTIONS(*OMIT) but couldn't 
actually test if it was *OMITted or not.  That has been fixed in newer 
release(s).

Ken
http://www.ke9nr.net/
Opinions expressed are my own and do not necessarily represent the views
of my employer or anyone in their right mind.