Re: [boost] Loki SmartPtr study: Policy orthogonality issues

From: Andrei Alexandrescu (andrewalex_at_[hidden])
Date: 2002-01-11 11:23:08

> I find the idea of enabling pointer arithmetic for shared_array somewhat
> questionable, but...
>
> shared_array in
>
> http://groups.yahoo.com/group/boost/files/smart_ptr_3.zip
>
> can be trivially extended to support it by adding
>
> shared_array & operator+= (std::ptrdiff_t i)
> {
>     px += i;
>     return *this;
> }
>
> Of course the BOOST_ASSERT(i >= 0); in operator[] will need to be removed.

But this operation is nonsensical in most, if not all, cases. Why would
someone need to alter a shared_array? It doesn't make sense; it means that
either before, or after the operation, the pointee array will be wrong.

I guess only operator+(int), operator-(int) should be allowed as pointer
arithmetic - if at all. operator-(T*) or operator-(sharte_array&) don't make
much sense, either.

Andrei

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