[boost] Re: best way to make {reverse_}fold a sequence

From: David Abrahams (dave_at_[hidden])
Date: 2005-02-28 20:35:03

Larry Evans <cppljevans_at_[hidden]> writes:

> On 02/28/2005 10:01 AM, David Abrahams wrote:
> [snip]
>>> 
>> That's misguided it seems to me.  Your tuple_type is not a
>> specialization of fold.  Are you really interested in making
>> specializations of fold into sequences?
>> You're folding some kind of cons cell, right?  Don't you want to
>> implement begin and end on that?
>>   template <class A, class B>
>>   struct begin<inherit<A,B> >
>>   {
>>      ...
>>   };
>> or something?
>
> Yes.  But how do I know what A or B is.  

??

At the point of ... the compiler knows what they are

> It has to be the result
> of size<Sequence>-1 applications of ForwardOp.  

Do you mean that you want to restrict the partial specialization
matching to only match your tuple types?  You don't have to use
inherit directly, you know; you could just derive your own my_inherit
class from it and match that in the partial specialization.  If you
only use my_inherit to build these tuples, you're home free.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com