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From: Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: Pointer to instance of indefinite array?
Date: Tue, 12 Aug 2014 21:28:14 -0700
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Date: 2014-08-12T21:28:14-07:00
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On 08/12/2014 08:06 PM, NiGHTS wrote:
>
> Hmm. You're right. It worked! Compiler must be changing it internally to a
> pointer though since it would be far too inefficient to copy the entire
> array.

The parameter-passing mechanism used by the compiler is generally not something 
we need to worry about.

Having to explicitly pass a pointer to obtain by-reference semantics is a mark 
of low-level languages. It is not a good way to do almost anything.

In a mid-level language, such as Pascal, one often specifies the 
parameter-passing mechanism, and the compiler uses that mechanism. This is 
pretty much what VAR (by reference) and non-VAR (by copy) parameters are in 
Pascal, though they're usually described in terms of whether or not changes to 
the formal parameter also change the actual.

In a high-level language, such as Ada, one specifies how the subprogram uses the 
parameter (in, in out, and out modes) and the compiler uses that and the type 
being passed to determine the parameter-passing mechanism.

-- 
Jeff Carter
"That was the most fun I've ever had without laughing."
Annie Hall
43