On Mar 1, 2006, at 00:59, RIVASSEAU Jean Noel wrote:

I quote the Boost serialization docs:

When serializing an object through a pointer to its base class and that base class is abstract (i.e. has at least one virtual function assigned a value of 0), A compile error will be emitted. This is addressable in one over several ways:

* remove the =0 in the base classes so that the base class is no longer abstract. * implement is_abstract for your compiler. (code written according to the C++ standard is included with this library. But it is known to fail on several compilers. * use the macro BOOST_IS_ABSTRACT(my_class) to indicate that the class is an abstract base class. This will cause the compiler to avoid generating code that causes this error.

I still do not understand part 2 of this advice, Robert. Could you explain?

The BOOST_IS_ABSTRACT macro expands into a specialization of the is_abstract template (in is_abstract.hpp) for the specified class, and returns mpl::bool<true> for the specified type. I think part 2 is a suggestion that a more general template may be written on a per-platform basis that properly returns mpl::bool<true> when the class is derived from an abstract base class. It's left as an exercise for the reader :) I'm not up to it right now myself...

Ps: as already mentioned, part 3 does not change anything for me, and I'd like to avoid the solution of part 1 since I do want the base class to be abstract.

I've found that it doesn't matter if you use BOOST_IS_ABSTRACT on the actual abstract base class, but you MUST (currently - 1.33.0) on the DERIVED class to get it to work "correctly". I'd consider this a bug, but I'm not sure of the specification and haven't had time to research it.