[boost] Re: boost::any: explicit constructor?

From: David Abrahams (dave_at_[hidden])
Date: 2004-03-01 08:41:28

Kevlin Henney <kevlin_at_[hidden]> writes:

> Information loss is not the deciding criterion for whether a conversion
> is narrowing or widening :-)
>
> Another distinction that needs to be made is that not all conversions
> fit into the widening/narrowing model. Some conversions are better
> considered as reinterpreting or translating conversions (eg lexical_cast
> and reinterpret_cast). These are useful where some notion of subtyping
> is not applicable, eg between int and string, as opposed to where one
> is, eg between numeric types.

I'm sympathetic to the idea that any should use implicit conversions,
but, really, are you saying that any has a subtype relationship with
everything it can hold?  If it did, then we could use any_cast on any
argument type, right?

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