Re: Constraint checking of actuals passed to Attributes

[Robert Dewar <robert_dewar@my-deja.com>]

In article <8f9c45$be5$1@nnrp1.deja.com>,
  Ted Dennison <dennison@telepath.com> wrote:
> Not having to have ever written a full Ada compiler, I'm not
> as aquainted with the nuances of the meaning of "abnormal" as
> it pertains to objects as many others here are.

The term "abnormal" has nothing to do with Ada compilers or any
other compilers, it is a term specifically coined for use in the
Ada RM, and fully defined therein.

> But my reading of the context of
> 13.9.1("Data Validity":3-7) implies more or less just that. It
> talks about objects that are "normal" having valid values for
> their type.

Nope, that's not careful enough reading. The whole point of
this section is to distinguish abnormal from other cases where
values may be outside the subtype range. An uninitialized
value is NOT abnorma. That's at the heart of the discussion
here, since referencing an abnormal object is for sure
erroneous:

8   It is erroneous to evaluate a primary that is a name
    denoting an abnormal object, or to evaluate a prefix that
    denotes an abnormal object.

But an uninitialized variable may well not have
a valid value.

Confused? I am not surprised. I find this whole attempt to
differentiate between these two states pretty ill-defined.

> So it would seem that any requirement to keep objects "normal"
> means that they cannot have garbage values placed in them.
> What am I missing?

See above!


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