Re: [boost] [type_erasure] Difficulties with const

13 Sep 2012

      AMDG

On 09/13/2012 01:42 PM, Christophe Henry wrote:
...
* ping *
I'm sorry.  I don't think I received the original message.
...
...
<snip>
namespace boost {
namespace type_erasure {
template<class C, class T, class Base>
struct concept_interface< ::getName<C, T>, Base, C> : Base
{
   T getName()
   { return call(::getName<C, T>(), *this); }
};
}
}
<snip>
This compiles and outputs as expected.
Problem 1: This will not compile
std::cout << "data: " << (*it).getName() << std::endl;
concept_interface<...>::getName needs to
be declared const for this to work.
...
...
Hmmm ok not so bad. I'll gladly pay the extra line. (interestingly, it
would compile and work without const)
Problem 2: if I use the MEMBER macro:
BOOST_TYPE_ERASURE_MEMBER((has_getName), getName, 0);
typedef any<
         mpl::vector<
             has_getName<std::string const&()>,
             relaxed_match,
             copy_constructible<>,
             typeid_<>
         >,
          const _self&
     >
AnyNameable;
Then the code does not compile, unless I accept to give up all of my
consts.
For a constant member function use:

has_getName<std::string const&(), const _self>
...
...
On one hand, I will find it a easier job to sell type_erasure with the
macro, OTOH, I will not give up my consts ;-)
Would it be possible to have the macro AND const-correctness?
In Christ,
Steven Watanabe