From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: Can't export object of private type
Date: 1999/03/02
Date: 1999-03-02T00:00:00+00:00 [thread overview]
Message-ID: <m3n21w7cnb.fsf@mheaney.ni.net> (raw)
In-Reply-To: F7xuGK.K6n@syd.csa.com.au
nospam@thanks.com.au (Don Harrison) writes:
> There is always a semantic gap between design and implementation in a
> particular language. Better languages, IMO, are those where that gap
> is uniformly narrow. For Ada, I think the gap is quite wide in places
> (eg. polymorphic singletons) and narrow in others (eg. low-level
> mapping).
I disagree about the polymorphic singletons. The spec looks like this:
package Singletons is
type Root_Singleton_Type (<>) is abstract tagged limited null record;
procedure Do_Something
(Singleton : access Root_Singleton_Type) is abstract;
<other primitive operations>
type Singleton_Access is access all Root_Singleton_Type'Class;
function Singleton return Singleton_Access;
end;
I wouldn't describe the semantic gap as "quite wide." The problem is
that few Ada programmers have learned the limited-and-indefinite
idiom.
So this idiom just needs to be publicized. You can find examples of
this idiom and others in the ACM patterns archive.
<http://www.acm.org/archives/patterns.html>
next prev parent reply other threads:[~1999-03-02 0:00 UTC|newest]
Thread overview: 128+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <F7JoCB.JxB@syd.csa.com.au>
1999-02-24 0:00 ` Can't export object of private type Don Harrison
1999-02-24 0:00 ` Tom Moran
1999-02-24 0:00 ` Samuel Mize
1999-02-24 0:00 ` Tucker Taft
1999-02-25 0:00 ` Don Harrison
1999-02-25 0:00 ` fraser
1999-02-26 0:00 ` Don Harrison
1999-02-26 0:00 ` Samuel Mize
1999-03-01 0:00 ` Don Harrison
1999-03-01 0:00 ` Matthew Heaney
1999-03-02 0:00 ` fraser
1999-03-03 0:00 ` Don Harrison
1999-02-26 0:00 ` fraser
1999-03-01 0:00 ` Don Harrison
1999-03-01 0:00 ` Matthew Heaney
[not found] ` <7b6nqe$75m$1@remarq.com>
1999-02-26 0:00 ` fraser
1999-02-27 0:00 ` Nick Roberts
1999-02-28 0:00 ` Matthew Heaney
1999-02-28 0:00 ` Matthew Heaney
1999-02-25 0:00 ` Samuel Mize
1999-02-26 0:00 ` Don Harrison
1999-02-27 0:00 ` Nick Roberts
1999-03-01 0:00 ` Don Harrison
1999-03-01 0:00 ` Matthew Heaney
1999-03-01 0:00 ` Nick Roberts
1999-03-01 0:00 ` Nick Roberts
1999-03-01 0:00 ` Don Harrison
1999-03-02 0:00 ` Matthew Heaney
1999-03-03 0:00 ` Don Harrison
1999-03-03 0:00 ` Samuel Mize
1999-03-04 0:00 ` Don Harrison
1999-03-07 0:00 ` Ehud Lamm
1999-03-03 0:00 ` Robert A Duff
1999-03-04 0:00 ` Don Harrison
1999-03-04 0:00 ` Robert A Duff
1999-03-01 0:00 ` Don Harrison
1999-03-02 0:00 ` Matthew Heaney [this message]
1999-02-28 0:00 ` Matthew Heaney
1999-03-01 0:00 ` Nick Roberts
1999-03-01 0:00 ` Matthew Heaney
1999-03-01 0:00 ` Matthew Heaney
1999-03-02 0:00 ` Nick Roberts
1999-03-01 0:00 ` Samuel Mize
1999-02-25 0:00 ` robert_dewar
1999-02-26 0:00 ` Don Harrison
1999-02-26 0:00 ` robert_dewar
1999-02-26 0:00 ` bourguet
1999-02-26 0:00 ` Samuel T. Harris
1999-02-27 0:00 ` Jean-Pierre Rosen
1999-02-27 0:00 ` Simon Wright
1999-02-28 0:00 ` dewar
1999-03-01 0:00 ` bourguet
1999-02-26 0:00 ` dennison
1999-03-01 0:00 ` Stephen Leake
1999-03-01 0:00 ` Don Harrison
1999-03-01 0:00 ` robert_dewar
1999-03-03 0:00 ` Don Harrison
1999-03-03 0:00 ` robert_dewar
1999-02-27 0:00 ` Brian Rogoff
1999-03-01 0:00 ` robert_dewar
1999-02-28 0:00 ` Matthew Heaney
1999-03-01 0:00 ` Tom Moran
1999-03-02 0:00 ` Matthew Heaney
1999-03-02 0:00 ` Tom Moran
1999-03-02 0:00 ` Matthew Heaney
1999-03-02 0:00 ` Tom Moran
1999-03-02 0:00 ` Matthew Heaney
1999-03-02 0:00 ` nabbasi
1999-03-02 0:00 ` Matthew Heaney
1999-03-03 0:00 ` Don Harrison
1999-03-03 0:00 ` Single Extension; Polymorphic Arrays Nick Roberts
1999-03-03 0:00 ` Nick Roberts
1999-03-08 0:00 ` Matthew Heaney
1999-03-08 0:00 ` Nick Roberts
1999-03-08 0:00 ` Tucker Taft
[not found] ` <m3ogm40wav.fsf@mheaney.ni.net>
1999-03-08 0:00 ` Nick Roberts
1999-03-08 0:00 ` Tucker Taft
1999-03-08 0:00 ` dennison
1999-03-09 0:00 ` Nick Roberts
1999-03-03 0:00 ` Can't export object of private type Don Harrison
1999-03-03 0:00 ` Don Harrison
1999-03-03 0:00 ` Nick Roberts
1999-03-04 0:00 ` Don Harrison
1999-03-04 0:00 ` fraser
1999-03-09 0:00 ` Don Harrison
1999-03-04 0:00 ` Nick Roberts
1999-03-04 0:00 ` robert_dewar
1999-03-05 0:00 ` Nick Roberts
1999-03-05 0:00 ` Robert A Duff
1999-03-05 0:00 ` Abstract Subprograms of Untagged Types Nick Roberts
1999-03-05 0:00 ` robert_dewar
1999-03-05 0:00 ` Tucker Taft
1999-03-05 0:00 ` Nick Roberts
1999-03-06 0:00 ` robert_dewar
1999-03-04 0:00 ` Can't export object of private type Nick Roberts
1999-03-08 0:00 ` Matthew Heaney
1999-03-09 0:00 ` Don Harrison
1999-03-09 0:00 ` Matthew Heaney
1999-03-09 0:00 ` Nick Roberts
1999-03-10 0:00 ` Don Harrison
1999-03-10 0:00 ` Matthew Heaney
1999-03-08 0:00 ` Matthew Heaney
1999-03-08 0:00 ` Nick Roberts
1999-03-08 0:00 ` Matthew Heaney
1999-03-10 0:00 ` Don Harrison
1999-03-10 0:00 ` Matthew Heaney
1999-03-10 0:00 ` dennison
1999-03-10 0:00 ` Robert A Duff
1999-03-10 0:00 ` dennison
1999-03-11 0:00 ` dennison
1999-03-10 0:00 ` robert_dewar
1999-03-10 0:00 ` robert_dewar
1999-03-10 0:00 ` dennison
1999-03-10 0:00 ` robert_dewar
1999-03-10 0:00 ` dennison
1999-03-11 0:00 ` robert_dewar
1999-03-11 0:00 ` Don Harrison
1999-03-12 0:00 ` robert_dewar
1999-03-11 0:00 ` bill
1999-03-11 0:00 ` dennison
1999-03-11 0:00 ` Scott Ingram
1999-03-11 0:00 ` Larry Kilgallen
1999-03-12 0:00 ` dewar
1999-03-11 0:00 ` dennison
1999-03-11 0:00 ` Don Harrison
1999-03-03 0:00 ` Don Harrison
1999-02-28 0:00 ` Matthew Heaney
1999-02-28 0:00 ` Matthew Heaney
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