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From: bobduff@dsd.camb.inmet.com (Bob Duff)
Subject: Re: Addressing functions
Message-ID: <D0rJn3.JH4@inmet.camb.inmet.com>
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Organization: Intermetrics, Inc.
References: <3citrc$bb5@earth.usa.net>
Date: Tue, 13 Dec 1994 19:04:15 GMT
Date: 1994-12-13T19:04:15+00:00
List-Id: <comp.lang.ada>

In article <3citrc$bb5@earth.usa.net>, Bill Buckley <wbuckley@earth> wrote:
> 
> ...I know I can get the address of a subprogram via the ADDRESS 
>attribute in Ada but can not figure a way to use it.

In Ada83, there is no portable way to call such a subprogram.  If you
know the machine-level calling conventions used by your compiler, you
can write a machine code insertion that does, but that's pretty nasty.

In Ada 9X, you can use access-to-subprogram types:

    type String_Procedure is access procedure (S: String);
    X: String_Procedure := Text_IO.Put'Access;

Now you can call X like this:

    X("Hello, world");

which means the same as this:

    X.all("Hello, world");
-- 
Bob Duff                                bobduff@inmet.com
Oak Tree Software, Inc.
Ada 9X Mapping/Revision Team (Intermetrics, Inc.)