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Subject: Re: [boost] [Interest] Value Dispatch
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2012-08-15 23:36:37


On 08/15/2012 06:34 PM, greened_at_[hidden] wrote:
> I was aiming for a value-centered analogue to virtual functions as
> opposed to an enhanced union type.

Well, what you have is essentially a union type,
even if that's not what you intended.

> boost::variant feels opaque to me
> (get<>, etc.) while value dispatch seems more natural and transparent
> for the use cases I had in mind.

You should avoid using get<> on a variant.
Whenever possible, apply_visitor is better.

> Note also that boost::variant appears to require or at least encourage
> inheritance (e.g. static_visitor) while value dispatch does not. I
> don't think that's a strong positive or negative as long as value
> semantics are maintained.

Boost.Variant doesn't care about inheritance.
static_visitor is like std::iterator or
std::binary_function. It's just a helper
that provides a result_type typedef.
Anyway, static_visitor is for apply_visitor
and doesn't have anything to do with the
types stored in the variant.

In Christ,
Steven Watanabe

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