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From: claveman@grzorgenplatz.net (Charles H. Sampson)
Newsgroups: comp.lang.ada
Subject: Subprogram Pointer in a Generic
Date: Wed, 16 Apr 2003 18:53:56 -0700
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Date: 2003-04-16T18:53:56-07:00
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     I'm using a procedure that takes a procedure pointer as an
argument.  It's pretty standard stuff:

          type Parameterless_Proc_Ptr is access procedure;
          procedure Register (The_Proc : in Parameterless_Proc_Ptr);

     My problem occurs when I want to call this procedure from within a
generic package.  I can't, because 3.10.2(32) says "If the subprogram
denoted by P [the prefix of 'Access] is declared within a generic body,
S [the access-to-subprogram type of the formal parameter] shall be
declared within the generic body."

     Now that's no good for me at all, so I've kludged my way around it
by taking the address of the actual argument procedure and changing it
to a pointer using Unchecked_Conversion, a technique guaranteed to work
for the current version of my current compiler on my current target
machine.

     There are two questions.  (1) What are they trying to prevent by
this restriction?  (2) Is there a more robust way of working around it?

                                Charlie

-- 
     For an email response, my real user name is csampson and my ISP is
inetworld.net.