Re: [Boost-users] [serialization] Attaching arbitrary data to an archive

Subject: Re: [Boost-users] [serialization] Attaching arbitrary data to an archive
From: Robert Ramey (ramey_at_[hidden])
Date: 2010-06-01 15:04:04

Noah Roberts wrote:
> Sometimes during serialization an object needs to know a lot more than
> it does during normal operation.  The way I've dealt with this in the
> past is to subclass the archive I want to use and add setter/getters
> for the data that various objects down the line are going to need to
> store and retrieve themselves.
>
> Is there a better way though, something that's built into the library
> already maybe?  I don't see anything but I thought I'd ask.

I needed this to implement serialization for shared_pointers.  For this 
reason
if you look into text_iarchive.hpp you'll see the "shared_pointer_helper".
That is, I subclassed the "naked_text_iarchive". with multiple inheritance.
This works well for me.

Except one thing....

I've now built in a dependency into ...archive to shared_ptr.  Sometime
ago, I had an undocumented concept "attach runtime helper".  I saw this
as "polluting" the otherwise "pristine" archive code with something that
didn't belong there so I factored it out and made is specific to
shared_pointer_helper.  I see now that the second decision was a mistake
and that I should have left it generic after I factored it out.

So the definitive solution is:

a) replace shared_pointer_helper with a "generic runtime helper".
b) adjust shared_pointer_helper interface to be an instance of the above
c) document all this.

Feel free to take this on.

Robert Ramey