[Boost-users] boost::fusion::set

Subject: [Boost-users] boost::fusion::set
From: Lukasz K (lukasz.emails_at_[hidden])
Date: 2012-12-12 11:59:33

Could someone explain to me why the following is a valid definition of
a boost::fusion::set?

        typedef boost::fusion::set<char,char,char> S;
        S s('a','b','c');

Especially, given that according to description:  "set is an
Associative Sequence of heteregenous typed data elements. Type
identity is used to impose an equivalence relation on keys. The
element's type is its key. A set may contain at most one element for
each key. Membership testing and element key lookup has constant
runtime complexity (see Overloaded Functions). "

Src: http://www.boost.org/doc/libs/1_52_0/libs/fusion/doc/html/fusion/container/set.html

Thanks, Lukasz