From: Edward Diener [mailto:eddielee@tropicsoft.com]

...

The intention was to call do_somethin on 'v.value()' but non-explicit ctor is happy to accept 'variable', after which 'do_something' breaks.

This is a programming error, not an error in boost::any.

Absolutely, but it's an error that could have been detected by the compiler given an explicit constructor. [snip]

While I am not against syntactic sugar which make it easier to use C++ constructs, I am against making a constructor explicit just to keep programmers from making errors.

Isn't keeping programmers from making errors a Good Thing? For me, that's exactly the reason why boost::any's constructor _should_ be explicit. Bjorn