First, thanks!
David B. Held wrote:
> "Philippe A. Bouchard" <[EMAIL PROTECTED]> wrote in message
> b1tvp7$da3$[EMAIL PROTECTED]">news:b1tvp7$da3$[EMAIL PROTECTED]...
[...]
> Here's the "raw pointer c'tor":
>
> template <typename U>
> smart_ptr(U const& p)
> : base_type(p, detail::init_first_tag())
> { checking_policy::on_init(get_impl(*this)); }
Great to know there is now some pre-condition like checking_policy.
> Here's what your storage_policy might look like:
>
> template <typename T>
> class shifted_storage
> {
> public:
> typedef shifted_object<T>* stored_type; // the type
> of the pointee_
> typedef shifted_object<T const>* const_stored_type; //
One little thing: the pointee_ must be of type T * because of polymorphic
objects with multiple inheritance that keep shifting the pointer implicitly;
and to have a fast operator *.
> object typedef T* pointer_type; // type
> returned by
> operator->
> typedef T const* const_pointer_type;
[...]
> shifted_storage(pointer_type p)
> : pointee_(static_cast<stored_type>(
> static_cast<char*>(static_cast<void*>(p)) -
> sizeof(shifted_header)
> ))
> { }
> // I think the arithmetic above is valid, because we're
> dealing with // POD types, but IANALL, so take it with a
> grain of salt
Maybe it would be better to use 'shifted_address<size_t, size_t>::get()'
instead of 'static_cast<void*>(p)) - sizeof(shifted_header)' because
pointer_type does not necessarily point to the beginning of the object.
[...]
> public:
> friend inline pointer_type get_impl(shifted_storage const& sp)
> { return &sp.pointee_->m_object; }
>
> friend inline stored_type& get_impl_ref(shifted_storage& sp)
> { return sp.pointee_; }
[...]
> protected:
> void release()
> { pointee_ = 0; }
>
> static stored_type default_value()
> { return 0; }
>
> private:
> stored_type pointee_;
>
> public:
> BOOST_MPL_AUX_LAMBDA_SUPPORT(1, shifted_storage, (T))
> };
>
> #ifdef __BORLANDC__
> namespace mpl { BOOST_MPL_AUX_VOID_SPEC(1, shifted_storage) }
> #endif
>
> Dave
It's interesting to know that some checking_policy is provided. It kind of
open doors to test the validity of the address at run-time. Conversions
will be interesting also.
Philippe A. Bouchard
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