Re: [boost] [assign] ptr_list_of legal?

From: Thorsten Ottosen (thorsten.ottosen_at_[hidden])
Date: 2007-05-31 02:07:14

shunsuke skrev:
> Thorsten Ottosen wrote:
>> shunsuke skrev:
>>> Hi,
>>>
>>> I found a snippet from <boost/assign/ptr_list_of.hpp>:
>>>
>>>     template< class T >
>>>     class generic_ptr_list
>>>     {
>>>         // ...
>>>     public:
>>>         template< class PtrContainer >
>>>         operator std::auto_ptr<PtrContainer>() const
>>>         { .. }
>>>     };
>>>
>>> IIRC, this automatic conversion doesn't work on any conforming compiler.
>> Why?
> 
> The rule seems complicated. :-(
> This is because it requires two user-defined conversions?
>    generic_ptr_list -> operator auto_ptr() -> operator auto_ptr_ref() -> auto_ptr
> 
> In the case of lvalue:
>    generic_ptr_list -> operator auto_ptr&() -> auto_ptr
> 
> I hope a lawyer will look into this posting. :-)

ME to.

It's no secret that some compilers had problems with it, but if IIRC, 
comeau could do it.

-Thorsten