Re: [boost] Re: Copy Constructible Concept

From: Gennaro Prota (gennaro_prota_at_[hidden])
Date: 2002-11-15 15:36:10

--- Douglas Gregor <gregod_at_[hidden]> wrote:

[...]
> For reference, the address of an object can be retrieved without using
> the address-of operator with the following function template:
> 
>   template <typename T> T* addressof(T& v)
>   {
>     return reinterpret_cast<T*>(
>          &const_cast<char&>(reinterpret_cast<const volatile char &>(v)));
>   }
> 
> Note: this relates directly to library issue 350, which will need to
> be reexamined if the CopyConstructible requirements change.
> 
> Proposed resolution:
> 
> Remove the last two rows of Table 30, eliminating the requirements
> that &t and &u return the address of t and u, respectively.

Thank you very much for your reply. The text confirmed what I suspected from
your previous words (suspect that is why I asked you to post the text itself),
i.e. that you prefer to drop any requirements on operator& instead of inventing
a separate concept (say "Addressable") for them. The problem I see in your
resolution is that AFAIK addressof() is not guaranteed to work by the standard.
Yes, it has an extremely high probability to do the right thing, but not a
guarantee. So I think either we find another portable way to take the address
or invent a new concept (which I like, though of course it requires more
changes to the standard)

Genny.

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