Boost C++ Libraries: Ticket #1941: polymorphic archive interface doesn't match other archive interfaces

status changed

Robert Ramey — Sun, 08 Jun 2008 04:37:51 GMT

status new → assigned

I'm looking at this and I don't see anything obvious. Send me a small example.

RObert Ramey

anonymous — Sun, 08 Jun 2008 05:08:16 GMT

Try calling get_library_version() on a polymorphic_xml_iarchive instance.

The problem is that polymorphic_iarchive_dispatch has the get_library_version() method declared as private. But the same method is public on other archives, like a binary_iarchive.

Robert Ramey — Tue, 10 Jun 2008 05:33:58 GMT

get_library_version() is public in the base class. Since its virtual function it dispatches through the vtable to the derived class function with the same name. The one in the derived class may be - and if fact should be - private. This prevents users from calling intothe dispatch directly and there by breaking the polymorphic design.

You shouldn't even be including polymorphic_iarchive_dispatch.hpp in your code - either directly or indirectly. Check out the manual and examples.

you can send me a small example which illustrates the problem and I'll look at it.

RObert Ramey

status changed; resolution set

Robert Ramey — Tue, 10 Jun 2008 20:43:39 GMT

status assigned → closed
resolution → invalid

anonymous — Wed, 18 Jun 2008 03:16:51 GMT

Here's the code that was causing me the grief:

Create the target archive object, as input boost::archive::polymorphic_binary_iarchive targetData(std::ifstream(sourcePath.external_directory_string().c_str()));

If the versioning implies that an update is not required if(targetData.get_library_version() == mTypeVersions[GetType(asset)]) {

Load from the target ...

}

status changed; resolution deleted

anonymous — Wed, 25 Jun 2008 02:35:51 GMT

status closed → reopened
resolution invalid

Re-opening the comment so that the sample problem code provided can be looked at

status changed; resolution set

Robert Ramey — Sun, 29 Jun 2008 15:23:36 GMT

status reopened → closed
resolution → fixed

The whole point of the polymorphic archive is to permit usage of a common interface without depending on the specific one. So really one is expected to use the base class "accessors"

try the following:

// Create the target archive object, as input
boost::archive::polymorphic_iarchive &targetData =
    boost::archive::polymorphic_binary_iarchive targetData(
        std::ifstream(sourcePath.external_directory_string().c_str())
    );
// If the versioning implies that an update is not required
if(targetData.get_library_version() == mTypeVersions[GetType?(asset)]) {
// Load from the target // ...
}

If that fails let me know.

Robert Ramey

milestone deleted

Mon, 03 Nov 2008 14:20:34 GMT

milestone Boost 1.35.1

Milestone Boost 1.35.1 deleted