Re: [Boost-users] [boost] [serialization] New Primitive Types

From: Robert Ramey (ramey_at_[hidden])
Date: 2007-11-23 11:09:21

Andy Tompkins wrote:
> Hi,
>
> If I create a new class, my_class, am I allowed to mark it as follows:
>
> BOOST_CLASS_IMPLEMENTATION
>  ( my_class
>  , boost::serialization::primitive_type
>  )
>
> The comments in level.hpp say that it won't call serialization code,
> thus I believe (and experience) that I don't need to provide either:
>
> template<class Archive>
> void my_class::serialize(Archive &ar, const unsigned int version)
> or
> template<class Archive>
> void serialize(Archive &ar, my_class &t, const unsigned int version)

correct.

> The comments also say that 'It presumes a member function or template
> in the archive class that can handle this type.'

correct.

> Does this mean that
> current archives (text, xml, and binary) are not able to use new
> primitive types without altering the archive to handle the new
> primitive?

My first answer was "correct"

> As I try it, both the text and xml archives use stream operators to
> convert my_class to a string and archive that.  The binary archive
> casts my_class to a void* and outputs sizeof(my_class) bytes to the
> archive. It this expected behavior?

But now you make me think about it,   It turns out that all the archives
mentioned have a default "fallback" for anything marked "primitive".

So,

a) You could mark anything primitive.
b) In binary archives it will still work just by copying/restoring the 
bitstream
c) In text based archives it will work if and only if there are stream << 
and >>
operators for the type.

Robert Ramey