I have written a union-style type similar to boost::variant which allows single values, and multiple types. This type is called a union-list ( ul ) and is described at http://www.codeproject.com/useritems/union_list.asp I will be honest, there are several disadvantages of the union-list when compared to boost::variant 1. Declaration style is uglier : typdef ul<int, ul<char, ul<float, ul<string, ul_end> > > > my_union_list; 2. the data size is huge = summation of the size of the individual types plus sizeof(bool) * #types. 3. union-list has very few features The advantages (and my motivation for creating it) of the union-list is that it requires no other boost libraries and has a very tiny code base. Another difference ( but not neccessarily an advantage ) of the union-list is that it uses and provides an index to access the type of its contents. I don't know if this is sufficient to warrant eventual submission as a boost mini-library. Any comments? In general I am curious about how other boosters feel about boost library sizes and inter-library couplings. For me this is a big obstacle to using boost in many circumstances. It doesn't seem to be a concern at all for the boost community, but I wonder if other programmers have similar sentiments and find themselves often seeking out simpler alternatives. Christopher Diggins http://www.cdiggins.com http://www.heron-language.com