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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Limited use for limited with?
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Date: Tue, 28 Sep 2010 15:45:53 +0200
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Date: 2010-09-28T15:45:53+02:00
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On Tue, 28 Sep 2010 05:59:59 -0700 (PDT), Maciej Sobczak wrote:

> Hiding the use of access values behind the scenes (by virtue of tagged
> types being always passed by reference) would obstruct the code
> without clear benefit.

The benefit is clear - no access types.

> This is what AWS does in its other versions of
> Start, but I don't like it.
> 
> I want to express this:
> 
> 1. Object is an interface type for the callback that will be
> implemented by user.
> 2. Object_Access is a type that will be used for declaring and passing
> around callback references. I don't want everybody to define their own
> types for what is a common functionality.

You should register the object itself rather than its pointer. Use a
constructing function which registers the object by placing it in a list or
do an explicit call to Register. Upon finalization Finalize would remove it
from there. The type of the object must be limited of course. This is the
schema I am using.

> BTW - it is exactly for the fact that there is little need for dynamic
> allocation that Object_Access has to be "access all" and not just
> "access".

I tend to avoid "all" everywhere I can.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de