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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Subtype or derived type?
Date: Mon, 9 Oct 2017 16:50:18 -0500
Organization: JSA Research & Innovation
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"Victor Porton" <porton@narod.ru> wrote in message 
news:orauq5$9tv$1@gioia.aioe.org...
...
> I have two variants in mind:
>
> 1.
>
> subtype Node_Type is Term_Type;
>
> 2.
>
> type Node_Type is new Term_Type;
>
> Please advise which of the two is better.

It depends on how you want to use the type/subtype, of course.

If you need overridding/overloading, then you probably want a new type (a 
derived type), so the compiler can differentiate. If you need to convert 
back and forth a lot, you probably want a subtype (so the conversions are 
implicit rather than explicit). And so on...

                            Randy.