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From: stt@houdini.camb.inmet.com (Tucker Taft)
Subject: Re: Modest proposal, 2 of 3
Date: 1996/11/26
Message-ID: <E1I340.8M8.0.-s@inmet.camb.inmet.com>#1/1
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sender: news@inmet.camb.inmet.com (USENET news)
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references: <575ag6$rt6@netline-fddi.jpl.nasa.gov>
organization: Intermetrics, Inc.
newsgroups: comp.lang.ada
Date: 1996-11-26T00:00:00+00:00
List-Id: <comp.lang.ada>


Van Snyder (vsnyder@math.jpl.nasa.gov) wrote:

: ...
: PROPOSAL for next standardization of Ada

: Allow objects to be declared in the public part of a package
: specification with mode "out".  The meaning is that clients of the
: package can reference the variable, but can't store into it.

This can pretty much be accomplished in Ada 95 as follows:

   package P is
       type T is private;
       type T_Reader is access constant T;
       Read_Only_Global : constant T_Reader;
     ...
   private
       Global : aliased T;  -- Global variable
       Read_Only_Global : constant T_Reader := T'Access;
   end P;

You could also create a rename of "Read_Only_Global.all" if need be,
perhaps in a child package.

: ...
: What fraction of Americans believe   |  Van Snyder
: Wrestling is real and NASA is fake?  |  vsnyder@math.jpl.nasa.gov

--
-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Cambridge, MA  USA