From: stt@houdini.camb.inmet.com (Tucker Taft)
Subject: Re: Y2K Issues
Date: 1998/10/29
Date: 1998-10-29T00:00:00+00:00 [thread overview]
Message-ID: <F1Lt90.HEx.0.-s@inmet.camb.inmet.com> (raw)
In-Reply-To: 71aejn$ped$1@nnrp1.dejanews.com
dewar@gnat.com wrote:
: In article <F1LGL1.B6F.0.-s@inmet.camb.inmet.com>,
: stt@houdini.camb.inmet.com (Tucker Taft) wrote:
: > Users *are* allowed to add grandchildren to package Ada.
: > They may not add "direct" children to package Ada (nor may vendors,
: > for that matter) -- see RM95 A.2(4).
: I find this a very odd claim. In RM A(4) we have
: Implementation Permissions
: 4 The implementation may restrict the replacement of language-defined
: compilation units. The implementation may restrict children of
: language-defined library units (other than Standard).
: ... But
: the paragraph I quoted above clearly allows a compiler to forbid the addition
: of children of packages in Ada unless I am really missing something!
Good point, Robert.
So, some compilers might allow user-defined grandchildren of Ada, while
others might not, so it is not a portable capability. Even if it
were allowed by all relevant compilers, as Robert points out below,
the actual code of the (grand)child would probably not be portable,
since presumably it would depend on implementation-specific
private types.
(FWIW, from my point of view, the fact that the code for such
grand-children is likely to be implementation-specific doesn't seem like
enough of a reason to disallow them, since the whole point may be to provide
a stable interface to some additional functionality via a
grand-child, recognizing that the implementation of the functionality may
need to be revised when porting to a new compiler or new release. Clearly
the "caveat emptor" is critical here.)
: Robert Dewar
: Ada Core Technologies
: P.S. Why don't we want customers adding grandchildren of Ada -- simple, they
: would potentially depend on internal private parts of the implementation of
: these packages which we feel free to change without notice at any time!
--
-Tucker Taft stt@inmet.com http://www.inmet.com/~stt/
Intermetrics, Inc. Burlington, MA USA
An AverStar Company
next prev parent reply other threads:[~1998-10-29 0:00 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-10-19 0:00 Y2K Issues John J Cupak Jr
1998-10-19 0:00 ` dewar
1998-10-19 0:00 ` Tucker Taft
1998-10-19 0:00 ` Joe Gwinn
1998-10-20 0:00 ` Joe Gwinn
1998-10-19 0:00 ` Niklas Holsti
[not found] ` <362B8D2F.802F42E6@lmco.com>
1998-10-20 0:00 ` Robert I. Eachus
1998-10-22 0:00 ` Mark Bennison
1998-10-22 0:00 ` dennison
1998-10-23 0:00 ` Robert I. Eachus
1998-10-20 0:00 ` dennison
1998-10-23 0:00 ` Michael F Brenner
1998-10-25 0:00 ` Michael Feldman
1998-10-26 0:00 ` dennison
1998-10-27 0:00 ` dewarr
1998-10-27 0:00 ` Tucker Taft
1998-10-27 0:00 ` Y2K Issues (well, not really...) Dave Wood
1998-10-28 0:00 ` Y2K Issues dennison
1998-10-28 0:00 ` Dave Wood
1998-10-27 0:00 ` John Herro
1998-10-26 0:00 ` Robert A Duff
1998-10-26 0:00 ` Joel Seidman
1998-10-26 0:00 ` Y2K Issues - Warning Off-Topic Al Christians
1998-10-27 0:00 ` Y2K Issues dewarr
1998-10-27 0:00 ` dewarr
1998-10-29 0:00 ` system
1998-10-29 0:00 ` Al Christians
1998-11-02 0:00 ` Marin David Condic
1998-11-04 0:00 ` Robert I. Eachus
1998-11-05 0:00 ` dewarr
1998-11-06 0:00 ` Jerry van Dijk
1998-11-07 0:00 ` dewarr
1998-11-06 0:00 ` Al Christians
1998-11-08 0:00 ` Jerry van Dijk
1998-11-08 0:00 ` dewarr
1998-11-06 0:00 ` Robert I. Eachus
1998-10-27 0:00 ` Gautier de Montmollin
1998-10-28 0:00 ` adam
1998-10-29 0:00 ` Gautier.DeMontmollin
1998-10-28 0:00 ` adam
1998-10-28 0:00 ` Al Christians
1998-10-29 0:00 ` Samuel Mize
1998-11-04 0:00 ` Robert I. Eachus
1998-10-28 0:00 ` Arthur Evans Jr
1998-10-28 0:00 ` dewar
1998-10-28 0:00 ` Gautier.DeMontmollin
1998-10-28 0:00 ` Jean-Pierre Rosen
1998-10-28 0:00 ` Robert I. Eachus
1998-10-29 0:00 ` Dale Stanbrough
1998-10-29 0:00 ` Tucker Taft
1998-10-29 0:00 ` dewar
1998-10-29 0:00 ` Tucker Taft [this message]
1998-10-30 0:00 ` dennison
1998-10-31 0:00 ` dewarr
1998-11-02 0:00 ` dennison
1998-10-30 0:00 ` Matthew Heaney
1998-10-31 0:00 ` dewar
1998-10-30 0:00 ` Dale Stanbrough
1998-10-29 0:00 ` Mark A Biggar
1998-10-29 0:00 ` Samuel Mize
-- strict thread matches above, loose matches on Subject: below --
1998-10-23 0:00 Condic, Marin D.
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