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From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: What is wrong here? (Generic and controlled types)
Date: 2000/04/06
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In article <873dp3hv8x.fsf@deneb.cygnus.argh.org>,
  Florian Weimer <fw-usenet@deneb.cygnus.argh.org> wrote:
> Robert Dewar <robert_dewar@my-deja.com> writes:
>
> |    29.    package Real_Vectors is new Generic_Vectors(Real,
Index, Zero);
> |           |
> |        >>> instantiation error at generic_vectors.ads:23
> |        >>> controlled type must be declared at the library
level
> |        >>> instantiation error at generic_vectors.ads:75
> |        >>> controlled type must be declared at the library
level
>
> > P.S. it is hard to see how the GNAT message could be any
> > clearer, suggestions welcome!
>
> I didn't understand this message, either.  AFAIK, the term
"library
> level" is not mentioned in Cohen's book -- the one I used (at
least,
> it's not listed in the index).


Actually I think library level is a pretty fundamental concept,
it simply corresponds to the intuitive and informal notion
of global. You certainly do NOT need to understand accessibility
levels to understand this concept, and it is a very basic one.
Odd that Cohen does not mention it, one is always at the mercy
of idiosyncrasies of text books :-)

But you are right, probably the use of the term local or global,
while not so technically accurate would be clearer.

perhaps something like

library (global) level

might get the best of both worlds?


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