Re: [Boost-users] [serialization] Serializing derived templateclassvia base pointer

17 Jan 2013

      ...
On Jan 17, 2013, at 2:01 PM, "Robert Ramey"  wrote:
...
Daniel Mitchell wrote:
...
Hi everyone, has any progress has been made on a general solution
for this problem? Given classes like these,
struct base {
template<typename Archive>
void serialize(Archive& ar, unsigned version) { }
virtual ~base() = default;
};
template<typename T>
struct derived : base {
template<typename Archive>
void serialize(Archive& ar, unsigned version) { ar & data; }
T data;
};
is it possible to serialize the derived type (with T unknown) via a
base pointer? Sticking a call to register_type<derived> in
derived::serialize doesn't seem to do it.
There are several demos in the examples directory which show how to
do this.
Robert Ramey
Daniel Mitchell wrote:
...
Hi Robert, thanks for your reply. Unfortunately I couldn't find any
of the demos to which you refer, but I did find a 2005 boost-users
thread on the subject:
http://thread.gmane.org/gmane.comp.lib.boost.user/13244/
In that discussion you said you did not have a general solution. I'm
just wondering if anything has changed since then e.g maybe C++11
makes a solution possible.
I looked at this thread and don't think it's relevant to your question.
But then I looked at your question again and see that I don't really 
understand it.

case 1

given a virtual base class A and a derived class B, serialize B (and any 
other
derivatives of A) through a pointer to the base class A.

This case is amply covered by the documentation and by examples in test
and example library directories - see test_dll_exported, etc..

case 2

we have a class  A which is a template so it's declared like:

template<class T>
class A {
...
};

and class B is derived from it.  Currently one would have to apply the
"export" or "registration" functionality to each instance of A<T> created.
I believe that the thread referred to above addresses this question.
And indeed, I have no answer to this question.  It might be possible
using some version of "enable_if" but I have done no work in this area.

Robert Ramey