[boost] [serialization][trunk] please bring us archive helpers back

From: Joaquín Mª López Muñoz (joaquin_at_[hidden])
Date: 2007-09-05 09:49:44

Hello,

Boost.Serialization 1.33-1.34 introduces the notion or "helpers" to the
Archive
interface by means of the member functions:

  void lookup_helper(
    const extended_type_info* const eti,
    shared_ptr<void>& sph);
  void insert_helper(
    const extended_type_info* const eti,
    shared_ptr<void>& sph);

which allow the user to make an archive instance store arbitrary helper
objects
associated to any given type. This helper interface is used to implement

serialization of boost::shared_ptr in a non-intrusive way, which was
impossible
for former versions of Boost.Serialization. This is a wonderful addition

to the library because not only solves the old problem with
serializating
shared_ptr but also serves as a general utility for implementing
complicated
serialization schemes, notably those in which internal resources are
serialized
which cannot be directly manipulated from the class public interface.

I have used archive helpers to good effect in implementing an otherwise
unfeasible serialization algorithm for a library I'm writing, but when I
moved
from Boost 1.34 to the SVN trunk I discovered to my dismay that this
(admittedly undocumented) feature has been removed in favor of an ad-hoc

extension of the Archive interface (internally based on something
resembling
the former helper code) to specifically allow serialization of
boost::shared_ptr.
IMHO this is a step back because it singles out shared_ptr as a type
receiving special attention (vg. what will happen with
std::tr1::shared_ptr,
will the interface be augmented again to cope with this?) and primarily
because it deprives us developers from a very very powerful tool.

Could the helper interface please please be brought back to
Boost.Serialization? Thank you,

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo