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From: Colin Paul Gloster <Colin_Paul_Gloster@ACM.org>
Newsgroups: comp.lang.ada
Subject: Re: Runtime type selection
Date: Tue, 13 Oct 2009 10:45:41 +0000
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Date: 2009-10-13T10:45:41+00:00
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On Sun, 11 Oct 2009, Dmitry A. Kazakov wrote:

|----------------------------------------------------------------------------|
|"                                                                           |
|On Sun, 11 Oct 2009 09:41:54 -0700 (PDT), xorque wrote:                     |
|                                                                            |
|> I'd like to develop a program that processes a graph. The contents of     |
|> the graph are a random selection of objects of different types (all       |
|> elements may be of the same type or may all be different - assuming       |
|> there are enough types defined). By 'type' in this case, I am             |
|> referring to Ada types.                                                   |
|>                                                                           |
|> The basic problem is that I want to create an object of a type picked     |
|> at random, at runtime. I'm not entirely sure what my options are here.    |
|                                                                            |
|The problem is that graph nodes have nothing in common. Thus there is       |
|nothing except for the graph traversal operations you could implement on    |
|the graph as a whole.                                                       |
|                                                                            |
|[..]"                                                                       |
|----------------------------------------------------------------------------|

You made it sound as if a Visitor Pattern might work.