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Subject: Re: [boost] Interest in specialized types
From: Henning Basold (h.basold_at_[hidden])
Date: 2010-09-28 05:31:45

2010/9/27 vicente.botet <vicente.botet_at_[hidden]>:
> ----- Original Message -----
> From: "Henning Basold" <h.basold_at_[hidden]>
> To: <boost_at_[hidden]>
> Sent: Monday, September 27, 2010 3:26 PM
> Subject: Re: [boost] Interest in specialized types
>>  Am 24.09.2010 12:31, schrieb vicente.botet:
>>> Before refactoring the Opaque implementation, I wanted to know if you have worked on your proposal.
>> Hi,
>> I am sorry to say but I haven't. I'm in the middle of writing my
>> bachelor thesis so I don't have a lot of time right now. But my brains
>> works despite the body has no time :) So I have some ideas for use cases
>> but no time to write them down.
>> I see you have already integrated the idea into Opaque. So the basics
>> are already there. Are you satisfied with it and is there anything to do
>> in this area. Else I would use my time (if I should have some ;)) on
>> extending the idea.
> Yes, I have integrated your ideas into Opaque after posting this message. Your approach allows to define opaque types fpr underlying UDT :) I hope both approaches are now well integrated.
> I have reached to implement a transitive conversion, either implicit for public opaque type or explicit for private opaque types. I gues these kind of transitive conversion could also be used for new_types that are more restrictive than opaque types.

Sounds good. Hopefully you can propose it soon for inclusion so I can
use it in production code :)

>> PS: The concept could for example be used to implement a generalized
>> type erasure which could be used in a type safe manner.
> I don't understand completly. Could you explain a little more?

The idea is very similar to Boost.Function. That is you have a fixed
interface that one can use on arbitrary types. The concret type is
then hidden after construction. The only difference to Boost.Function
is that you can specify an arbitrary interface and not just function
calls. The interace specification is done analogously to new_type. So
one could use Boost.Any without having to know the concret type which
is stored inside (as long as the object itself isn't needed).
My only problem so far is that I haven't found a way that objects do
no grow in size or the dispatching in time with the number of possible

> Thanks,
> Vicente
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