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Date: 27 Jul 93 23:05:42 GMT
From: eachus@mitre-bedford.arpa  (Robert I. Eachus)
Subject: Re: Anyone else actually like Ada?
Message-ID: <EACHUS.93Jul27180542@spectre.mitre.org>
List-Id: <comp.lang.ada>

In article <1993Jul27.155947.11409@tinton.ccur.com> cjh@tinton.ccur.com (Christ
opher J. Henrich) writes:

   > In Ada83 you can achieve some of the same goals, by careful use of
   > generic units with subprogram formals. The decision about what code
   > to bind to the "formals" must be made at compilation time, and
   > the syntax of generic units makes it all seem much more rigid.

   For the one-millionth time...elaboration of generic instantiations
occurs at RUN-TIME.  It is always the case that a compiler can
determine at compile time the possible subprograms which will match a
particular generic formal parameter, but that in no way limits the
usefulness of the feature.  For example if you add:

   function "+"(L,R: My_Type) return My_Type is <>;

   at the end of a generic formal part with a generic formal type
My_Type, this will match the plus operator for the actual type which
is visible at the point of instantiation, instead of the predefined
operator for the type.

   Also most good Ada compilers do support calling of subprograms by
their address, and among those which do, the feature mixes cleanly
with generics.  What Ada 9X will add is the safety of parameter and
result profile matching.

--

					Robert I. Eachus

with Standard_Disclaimer;
use  Standard_Disclaimer;
function Message (Text: in Clever_Ideas) return Better_Ideas is...