Re: [boost] [gsoc] improving any and variant

Subject: Re: [boost] [gsoc] improving any and variant
From: Franz Fehringer (fehrin_at_[hidden])
Date: 2009-03-30 02:27:53

What happened to dynamic_any btw?
http://www.ddj.com/cpp/184403961

Mathias Gaunard schrieb:
> A few little ideas that could eventually be joined to be a single GSoC 
> project:
>
> - Allow visitation for Any. This can actually be generalized to any 
> object that exposes a type_info, such as polymorphic objects.
>
> Techniques, including non-portable ones based on name mangling, could 
> be experimented to get more efficient dispatch.
>
> - Add SBO to any.
>
> - Improve variant so that the functor doesn't require to expose a 
> result_type. The result_type can be automatically deduced by "joining" 
> all the possible return types obtained by boost::result_of.
>
> - Allow the easy construction of a visitor from lambda expressions, 
> with a syntax like
>
> variant<int, std::string> a = "foo";
>
> int b = match(a).with(
>    args<int>(_1),
>    args<std::string>(size(_1))
> );
>
> instead of the potentially more verbose
>
> struct my_visitor : static_visitor<int>
> {
>     int operator()(int a) { return a; }
>     int operator()(const std::string& b) { return b.size(); }
> };
>
> variant<int, std::string> a = "foo";;
>
> int b = apply_visitor(my_visitor(), a);
>
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