Re: [boost] Formal Review Request: TypeErasure

Subject: Re: [boost] Formal Review Request: TypeErasure
From: lcaminiti (lorcaminiti_at_[hidden])
Date: 2012-06-18 15:25:48

lcaminiti wrote
> 
> I will use the lib in some use cases that I ran into the past and let you
> know if I find a nice example not too complex (I don't remember what the
> use cases were but they were about type erasure).
> 

Is this a sensible use of this library or is there a much better way to do
the following?

#include <boost/type_erasure/any.hpp>
#include <boost/type_erasure/builtin.hpp>
#include <boost/type_erasure/operators.hpp>
#include <boost/mpl/vector.hpp>
#include <iostream>

struct display
{
    public: template< typename T >
    explicit display ( T const& obj ) : obj_(obj) {}

    public: void print ( void ) { std::cout << obj_ << std::endl; }

    public: boost::type_erasure::any<
        boost::mpl::vector<
              boost::type_erasure::copy_constructible<>
            , boost::type_erasure::typeid_<>
            , boost::type_erasure::ostreamable<>
        >
    > obj_;
};

int main ( void )
{
    display i(-1), d('x');
    i.print();
    d.print();
    return 0;
}

I had to do something like this in the past where:
1. I didn't want display to be a template but I wanted it to handle generic
types as passed to the constructor.
2. I knew a-priori the operations that display needed from T (e.g.,
operator<<).
3. I had to store the object of the generic type T so the operation on T
could be performed later (e.g., by print).
I needed to do this as an implementation detail so the original problem I
was trying to solve has little relevance in general. But I wanted to ask if
using this library is a reasonable approach to do the above of it there are
better ways.

Regards,
--Lorenzo

--
View this message in context: http://boost.2283326.n4.nabble.com/Formal-Review-Request-TypeErasure-tp4630373p4631477.html
Sent from the Boost - Dev mailing list archive at Nabble.com.