[boost] Re: boost::any: explicit constructor?

From: David Abrahams (dave_at_[hidden])
Date: 2004-03-09 08:57:02

Kevlin Henney <kevlin_at_[hidden]> writes:

> In message <uekscadmf.fsf_at_[hidden]>, David Abrahams
> <dave_at_[hidden]> writes
>>Kevlin Henney <kevlin_at_[hidden]> writes:
>>
>>> Another distinction that needs to be made is that not all conversions
>>> fit into the widening/narrowing model. Some conversions are better
>>> considered as reinterpreting or translating conversions (eg lexical_cast
>>> and reinterpret_cast). These are useful where some notion of subtyping
>>> is not applicable, eg between int and string, as opposed to where one
>>> is, eg between numeric types.
>>
>>I'm sympathetic to the idea that any should use implicit conversions,
>>but, really, are you saying that any has a subtype relationship with
>>everything it can hold?  If it did, then we could use any_cast on any
>>argument type, right?
>
> I'm not sure that I understand this wording. 

Me neither, at this point.

> Is there another way of phrasing this or perhaps a code fragment
> that would illustrate the point?

Maybe not.  Could we forget I ever asked the question? ;-)

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com