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From: Victor Porton <porton@narod.ru>
Newsgroups: comp.lang.ada
Subject: Re: Simple Components (Generic_Directed_Graph)
Date: Mon, 30 Oct 2017 16:58:53 +0200
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Date: 2017-10-30T16:58:53+02:00
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Dmitry A. Kazakov wrote:

> On 2017-10-30 11:41, Victor Porton wrote:
> 
>> I do not understand your logic in Generic_Directed_Graph:
>> 
>> The procedures like
>> 
>> procedure Disconnect (Parent : Node; Child : Node);
>> 
>> do not take "Graph" argument.
> 
> A graph consists of connected nodes. Each node is in and a graph.
> 
>> Does it mean that there exists just one graph (per instantiation)?
> 
> No. If two nodes are mutually unreachable you have two graphs.
> 
>> This looks wrong for me. First it is using global variables.
> 
> It uses referential semantics. Node is an access type to the type you
> pass to the package when you instantiate it. E.g. if you want a graph of
> Strings you instantiate the package with String. Then Node is a pointer
> to string.
> 
> The notion of scope does not really applied to the structures like
> graph. You can scope the pool you pass to the instance. You can scope
> nodes with some logic attached when a node leaves its scope. But
> otherwise it makes little sense to talk about the scope of a graph.

What's about having multiple graphs for the situation if when A and B are of 
type T then A=B implies A'Access=B'Access?

It seems in this situation we cannot have multiple graphs of nodes of type 
T.

It yet seems bad for me, but may I mistake.

Maybe it's worth to create an alternative graph type (with every graph being 
a full-fledged object)? However I do not quite understand your logic, maybe 
you are right after all and this is not necessary.

-- 
Victor Porton - http://portonvictor.org