Re: [boost] [type_erasure]any(U,static_binding) stores wrong type

Subject: Re: [boost] [type_erasure]any(U,static_binding) stores wrong type
From: Larry Evans (cppljevans_at_[hidden])
Date: 2012-07-29 10:48:08

On 07/29/12 08:06, Larry Evans wrote:
> When the attached is run, it produces output:
> 
> ./static_binding.exe
> std::is_copy_constructible<ph_erasee_type>=0
> 53:ph_ctor_arg<boost::type_erasure::_a>::CTOR.default:my_instance=0
> creating a_fst from a_ctor_arg
> 64:ph_ctor_arg<boost::type_erasure::_a>::CTOR.copy:my_instance=1:(void*)this=0x66ab50
> :*fst_cast=ph_erasee<boost::type_erasure::_a>.my_instance=0:(void*)fst_cast=0x66ab50
> dynamic_cast<ph_ctor_arg_type*>(value_base_ptr)=0x66ab50
> dynamic_cast<ph_erasee_type*>(value_base_ptr)=0
> 
> Indicating that a ph_ctor_arg_type is being stored in a_fst instead
> of the expected ph_erasee_type.
> 
OOPS, reading more closely the requires from:

it says:

  U is a model of Concept.

and obviously ph_ctor_arg_type is not because it occurs nowhere in
ConceptA; however, it would be clearer if the requirement were:

  U is a suitable argument to the copy constructor for
  mpl::map<Map, Tag>::type, where Tag is the 2nd template
  arg to the any to be constructed.

-regards,
Larry