Re: [boost] [review] conversion - Vladimir's comments

Subject: Re: [boost] [review] conversion - Vladimir's comments
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2011-08-30 17:02:51

Le 30/08/11 22:30, Vicente J. Botet Escriba a écrit :
> Le 30/08/11 20:33, Mathias Gaunard a écrit :
>> On 30/08/2011 19:38, Vicente J. Botet Escriba wrote:
>>
>>> Right. This doesn't mean that you can not use the library with
>>> specializations that don't conflict. Some useful examples are given for
>>> some Boost and STL classes. The idea is that the source and target
>>> specialization are enough concrete to avoid the conflict. If you 
>>> have an
>>> example of partial specialization that will conflict I could try to see
>>> how I would do it.
>>
>> Let's say I do a fusion sequence to string converter.
>> Then I do a proto expression to string converter.
>>
>> (Proto expressions are also fusion sequences)
>>
> Your are right. This is a good example as it is not reasonable to make 
> a specialization for fusion sequences that are no proto expressions. 
> As any concept can be refined we need to use another technique than 
> SFINAE to be able to specialize the refinement.
>
>
Thinking about it a little but more, the library can take care of 
concepte refiniment specialization defining some wrapping classes for 
each concept. So we could have a fusion_sequence_wrapper and a 
proto_expression_wrapper that inherits from fusion_sequence_wrapper.

Now we can define conversion specializations for 
fusion_sequence_wrapper<T> to string and fusion_sequence_wrapper<T> to 
string without using SFINAE. Of course, it will be better if the user 
didn't needed to wrap them explicitly.

Vicente