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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Derived private interface
Date: Mon, 1 Aug 2011 16:56:17 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2011-08-01T16:56:17-05:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:1rlxo1uthv5xt.1agapd9q0mek4$.dlg@40tude.net...
...
> BTW, Generic_Dispatching_Constructor of Ada 2005 did not change much to 
> Ada
> 95 because of tags. You still need a registering layer to maintain 
> external
> name to tag mapping.

It did eliminate one thing, the need to have a scheme to create an object of 
each tagged type. That forced the use of either a case statement or an 
access-to-subprogram, either of which is error-prone.

There is no possibility of eliminating the need for some sort of registry --  
although in some cases you can use the one built-into the language (the 
External_Tag). There has to be a mapping somewhere of some sort of key to a 
tag, since it isn't possible to export tags to the "real world".

                                Randy.