Re: Conditional compilation in Ada?

[Arthur Schwarz <aschwarz@acm.org>]

Dr. Adrian Wrigley wrote:
>>pragma Ignore ( -- compiler warning 
>> DEBUG.put_line
>> (  "Here " & Is.Something ("reasonable complex to evaluate")
>> )
>>);
> 
> 
> Maybe I'm being stupid, but how does this help?
> Doesn't this always have no effect?
> 
> I'd like to switch debugging on/off without editing every
> DEBUG statement in the source...

Same problem. What I usually do is use a flexible scheme to represent 
debug flags. If I want the code permanantly removed, I set the debug 
flags to:

     Debug_Flag : constant Boolean := FALSE;

and if I want the conde permanently available, I set the debug flags to:

     Debug_Flag : constant Boolean := TRUE;

and if I want to (interactive) change my mind, I set the debug flags to:

     Debug_Flag : Boolean := TRUE;

The pragma inline (below) conserves code and enables identification of 
debug sections - it is for a maintainer's notification and does nothing 
in terms of code or code integrity. And I know, I know, 'pragma inline' 
is only a suggestion to the compiler - but a good one.

The Is_Debug functions are tailored to suit. I've given only a clear (?) 
and simple presentation of principle.

Forgive the Ada.

Hope this provides a focus for conversation. It would be nice to see 
what debug things are out their.

art


Package one body is

Debug_Flag  : Boolean := TRUE;  // Note: this is a variable
                                 // and placed in the spec file.

function Is_Debug return Boolean is
begin -- Is_Debug
    return Debug_Flag;
end Is_Debug;
pragma inline( Is_Debug );


end one;

Package two body is

Debug_Flag  : Boolean := TRUE; // same as above

function Is_Debug return boolean is
begin -- Is_Debug
    return Debug_Flag and one.Is_Debug;
end Is_Debug;


procedure Some_Thing is
begin -- Some_Thing
    if ( Is_Debug ) then
      null;
    end if;
end Some_Thing;
end two;