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Date: 14 Oct 92 17:03:36 GMT
From: yale.edu!jvnc.net!netnews.upenn.edu!uofs!guinness.cs.uofs.edu!beidler@yal
e-bulldog.arpa  (Jack Beidler)
Subject: Re: Generic Instantiation as Subprogram Body?
Message-ID: <11225@platypus.uofs.uofs.edu>
List-Id: <comp.lang.ada>

In article <dnsurber.718567247@node_26400>, dnsurber@lescsse.jsc.nasa.gov (Doug
las N. Surber) writes:
|> 
|> The following code is what I want to write.  It doesn't work and I don't 
|> like that!
|> 
|>     generic
|> 	type T is range <>;
|>     package P is
|> 
|> 	type U is private;
|> 	
|> 	function "<" (l,r : U) return boolean;
|> 	function "<=" (l,r : U) return boolean;
|> 	function ">" (l,r : U) return boolean;
|> 	function ">=" (l,r : U) return boolean;
|> 
|>     private
|> 	 . . .

Since "<=" is equivalent to "not >" and ">=" is equivalent to "not <"

the package spec should be

     generic
 	type T is range <>;
     package P is
 
 	type U is private;
 	
 	function "<" (l,r : U) return boolean;
 	function ">" (l,r : U) return boolean;
 
     private
 	 . . .

Is it "Stoopid machine!" or  "Stoopid _____!"

In the package body

|> 
|> 	generic
|> 	    with function op(l,r : T) return boolean;
|> 	function rel (l,r : U) return boolean;
|> 
|> 	-- the following doesn't work. declared function name hides the
|> 	-- generic actual.
|> 	function "<" is new rel("<");
|> 	function "<=" is new rel("<=");
|> 	function ">" is new rel(">");
|> 	function ">=" is new rel(">=");
|> 
|> 	function rel (l,r : U) return boolean is
|> 	begin
|> 	    return op(l, r);   -- or whatever
|> 	end rel;
|> 
|>     end P;

since you have not shown what type "U" is, I am only guessing,
but if "U" is a record or array, "<", etc. are not defined, 
hence "<" has no meaning for type "U".  Insteaad of the contrived
generic function rel, supply the bodies of the ordering functions
for the type U,

  function "<" (l, r : U) return boolean is

     begin
        . . .

     end "<":

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|  John (Jack) Beidler				                   |
|  Prof. of Computer Science Internet: BEIDLER@JAGUAR.UOFS.ED      |
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