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From: "Jeffrey R. Carter" <jrcarter@acm.org>
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Newsgroups: comp.lang.ada
Subject: Re: Why does this work? (overloads)
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Jerry wrote:
>>
> Good point. However, it uses twice the memory, and worse, changes made
> in A are not reflected in B without repeating the assignment A := B
> (correct?) and vice versa. My Pascal trick had neither of these
> problems yet carried boundary checking using either name.

Right. But your Pascal trick is an abomination. You can do the same 
thing in Ada using overlays, but it's not recommended. There's probably 
also a way with access types. Something like (not tested)

type Vector is array (Natural range <>) of Real;

Max : constant := ...;

subtype Zero_Based is Vector (0 .. Max - 1);
subtype One_Based  is Vector (1 .. Max    );

type Zero_Ptr is access all Zero_Based;
type One_Ptr  is access all One_Based;

V : aliased Zero_Based;

ZP : Zero_Ptr := V'access;

function To_One is new Ada.Unchecked_Deallocation
    (Source = Zero_Ptr, Target => One_Ptr);

OP : One_Ptr := To_One (ZP);

I wouldn't recommend it.

-- 
Jeff Carter
"What I wouldn't give for a large sock with horse manure in it."
Annie Hall
42