Re: [Boost-users] [mpl] trouble with conditionals

From: David Abrahams (dave_at_[hidden])
Date: 2005-10-05 08:53:24

Geoffrey Romer <geoff.romer_at_[hidden]> writes:

> OK, your correction works, but I don't understand why. I thought that
> omitting the typename ... ::type syntax just creates a null-ary
> metafunction. For example,
>
> pair<char, plus<int_<1>, at<m_map,char> >
>
> seems to me like it would produce not a pair consisting of a char and
> an int_, but a pair consisting of a char and a null-ary metafunction
> which, when applied, produces an int_. Am I missing something?

The 2nd argument to plus above probably isn't what you think.  You're
passing it a nullary metafunction: at<m_map,char>.

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