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From: Stephen Leake <stephen_leake@stephe-leake.org>
Newsgroups: comp.lang.ada
Subject: Re: What is your opinion on Global Objects?
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Date: Thu, 20 Nov 2014 10:34:28 -0600
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Date: 2014-11-20T10:34:28-06:00
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Hubert <herrdoktor@fumanchu.com> writes:

> That basically is a vote for global objects. Whether they are accessed
> through a global variable or some sort of getter function that returns
> access, it means bypassing the parameters. Well from what I read here,
> there are no strong opinions for either concept. Strange, I wasn't
> able to find good arguments for or against the two concepts anywhere,

If you can really, truly, absolutely guarrantee that you will _never_
need two different copies of the data structure, then the singleton
pattern makes sense (data in a single variable in a package body).

If you ever need two different copies of the data structure, then you
need to pass it around in parameters.

The symbol table for a compiler is a good candidate for a singleton.

A database connection is not; you will need to copy the database from
one object to another when you change the schema or move to a new
backend in the future.

-- 
-- Stephe