[boost] interest in 'tagged variant'? Useful in non-string spirit parsing.

From: Larry Evans (cppljevans_at_[hidden])
Date: 2007-12-05 17:19:28

A recent thread in spirit.general NG suggested to me the need for
a 'tagged variant' extension to boost::variant in order to emulate
the tagged-union mentioned in this post in the thread:

http://article.gmane.org/gmane.comp.parsers.spirit.general/12611

A prototype of such an extension is available in variant_tagged.zip
here:

http://www.boost-consulting.com/vault/index.php?&directory=Data%20Structures

Use of the variant_tagged could be used whenever non-string processing
is required in a spirit parser.  Each tag in the using corresponds to
a token-id and each value associated with that token-id is the attribute
for that token-id.  This closely emulates the way yacc does it, IIRC, 
except it just uses a union and the tag is somehow "implicit".

Is there any interest in using this in spirit or boost in general?