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From: Korcan Hussein (korcan_h_at_[hidden])
Date: 2006-12-14 13:10:05

"Steven Watanabe " wrote:
>Do you intend to make boost::any a typedef then?

That would do it unless there is some non-obvious ambiguity that this may

>Meaning boost::apply_visitor(printer, a) I assume?

Yep but an apply_visitor function isn't reallly necessary.

>Do you mean
>struct deref_print :
>boost::dynamic_visitor<std::vector<int>::const_iterator> { void
>operator()(std::vector<int>::const_iterator iter) const { std::cout
><< *iter; } };
>std::vector<int> v(1); boost::any a = v.begin();
>boost::apply_visitor(deref_print(), a);

Basically what i meant was you have 4 cases of:

     cosntant visitor visits constant and non-constant visitee
     non-constant visitor visits constant and non-constant visitee

     constant visitee accepts cosntant & non-constant visitor
     non-constant visitee accepts cosntant & non-constant visitor

>For this last I don't think there is a good non-intrusive solution.

Are you talking about the complete solution or catch-all part? i don't see
exactly how this is an intrusive solution so please elaborate/clarify.

>If the default is to throw an exception then it effectively limits the
>contained type to those enumerated. In this case it is probably better to
>use variant in the first place.

I don't see what the problem is since a user can override the default or
later extend there original visitor to support new (set) type(s), as well as
override the definition of the old supported types if he/she wishes. This
solution seems to be much better than type casting (for every type wanted) &
type switching code that you have to do with boost::any::.

If no one likes the idea of a default catch-all/generic visit and have a
better alternative then i'm open to it since this isn't set in stone and
isn't diffcult to change since the implementation is so trivial :)

Actually when i think about it the "catch-all" isn't even really
need/necessary, the original reason why i put it in in the first place was
as a constrast to generic visits of with boost::variant visitors.

Anyways it looks as if no one is interested, even just to make a comment of
any form :(

Korcan Hussien.

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