[boost] Re: Discovering array size - implementation as compile-timeconstant

From: Thorsten Ottosen (nesotto_at_[hidden])
Date: 2003-12-07 08:55:48

"Jonathan Turkanis" <technews_at_[hidden]> wrote in message
news:bquivn$ufp$1_at_sea.gmane.org...
> I skipped the thread about discovering array sizes until tonight, when I
> discovered I need the size of an array type as a compile-time constant -- 
> without partial specialization. Reading through the discussion, I didn't
> find a proprosed implementation.
>
> Is this simple implementation correct?
>
>     template<typename T>
>     struct array_size {
>         static const T* t;
>         BOOST_STATIC_CONSTANT(size_t, value = sizeof(T) / sizeof(*t[0]));
>     };
>
> For good measure, one could add
> BOOST_STATIC_ASSERT(boost::is_array<T>::value).

your implementation looks ok (I have not testet it), but the problem is
often that you want the size of a variable and not a
type, eg,

sizer( my_array_variable );

which makes the code look a lot different.

best regards

Thorsten