Re: [boost] Re: mpl::equal_to changes

From: Aleksey Gurtovoy (agurtovoy_at_[hidden])
Date: 2004-09-26 05:22:32

David Abrahams writes:
> Cromwell Enage <sponage_at_[hidden]> writes:
>
>> --- Ian McCulloch <ianmcc_at_[hidden]>
>> wrote:
>>> Hi,
>>
>> Hello.
>>
>>> Is the following program supposed to compile with
>>> the new MPL?
>>
>> Probably not.
>>
>>> But, maybe I was mis-using equal_to ?
>>
>> equal_to<...> no longer accepts bool_<...> or any
>> expressions resulting in bool_<...> as a template
>> argument, since bool_<...> does not contain a typedef
>> named tag (for numeric_cast<...>).  I don't have the
>> MPL book, so I don't know the rationale behind it
>
> Unfortunately, that bit isn't covered in the book.  I think Aleksey
> added the tag stuff very recently as a way of handling non-integral
> numeric types.  

Very-very recently.

> It seems to me that bool_ really ought to have
> whatever tags int_ has.

Yep.

-- 
Aleksey Gurtovoy
MetaCommunications Engineering