Re: ObjectAda vs Gnat -- bugs

[stt@houdini.camb.inmet.com (Tucker Taft)]

Tom Moran (tmoran@bix.com) wrote:

: I'm a little confused by this renaming of function return values.  If T
: is a limited type and F is a function returning T, then I understand one
: can:
:   X:T renames F(...);
: and one cannot
:   X:T := F(...);
: Is that correct?

Correct.

: If T is not limited, then what are the differences between
:   X : T renames F(...);
:   Y : T := F(...);

In the first case, X inherits the "constant"ness of the object
being renamed, which in this case, means that X is a constant.
In the second case, we have a new object, and since you left
off the word "constant" it is not a constant.

If you had written "Y : constant T := F(...);" then they would
be almost indistinguishable (though you wouldn't be able
to apply representation clauses to the rename, since you haven't
really declared a new object).

-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Burlington, MA  USA

P.S. For what its worth, enumeration literals really are treated
as functions in our Ada 95 front end symbol table.  It is just 
their "body" which is a bit funny -- it is intrinsic and all calls
are "expanded" inline. -TT