id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
3996,Enable use of BOOST_FOREACH over const-ref of noncopyable ptr_containers,Kazutoshi Satoda <k_satoda@…>,Thorsten Ottosen,"I have encountered an error about allocating abstract type, with the
following code:
{{{
#include ""boost/ptr_container/ptr_vector.hpp""
#include ""boost/foreach.hpp""
struct S { virtual void f() const = 0; };
typedef boost::ptr_vector<S> ptr_vector;
void f(ptr_vector const& v) { BOOST_FOREACH(S const& s, v) s.f(); }
}}}
And I found this is a known issue:
[http://www.boost.org/doc/libs/1_42_0/doc/html/foreach/extensibility.html#id862475 Boost.Foreach > Extensibility]

Then I thought that boost::foreach::is_noncopyable<> should be
specialized for ptr_containers of which value_type is abstruct. Then I
put the following:
{{{
namespace boost { namespace foreach {
  template<typename T, typename A, typenale CA>
  struct is_noncopyable<ptr_vector<T,A,CA> > : is_abstract<T> {};
}}
}}}
... and the error disappeared.

After that, since ptr_container is designed to be an alternative of the
standard containers for the case of the value is non-copyable, I thought
this is a wide problem worth making a patch.

The patch looks better than the above workaround in some points:
  - fixes the problem for all ptr_containers at once
  - also supports types marked by boost::noncopyable
  - keeps the container copyable if view_clone_allocator is used

The patch also includes some test cases I actually used, while I have no
idea how to integrate it into boost test infrastructure.
",Patches,reopened,To Be Determined,ptr_container,Boost Development Trunk,Problem,,BOOST_FOREACH is_noncopyable,jonathan.jones@…