From: Robert Ramey (ramey_at_[hidden])
Date: 2004-04-17 10:22:59
Matthias Troyer
> On Apr 13, 2004, at 9:42 PM, Robert Ramey wrote:
>> Making a new archive class is described in the section "New Archives -
>> Implementation". The model for an archive class is:
>
>> //////////////////////////////////////////////////////////////////////
>> ///
>> // class trivial_iarchive - read serialized objects from a input text
>> stream
>> class trivial_iarchive
>
>> : public boost::archive::common_iarchive<trivial_iarchive>
>> {
>> // permit serialization system priledged access to permit
>> // implementation of inline templates for maximum speed.
>> friend class boost::serialization::load_access;
>
>> // member template for loading primitive types.
>> // Override for any types/templates that special treatment
>> template<class T>
>> void load(T & t);
>
>> public:
>> //////////////////////////////////////////////////////////
>> // public interface used by programs that use the
>> // serialization library
>
>> // the >>> operator
>> template<class T>
>> trivial_iarchive & operator>>(T & t){
>> boost::serialization::load(* This(), t);
>> return * This();
>> }
>
>> // archives are expected to support this function
>> void load_binary(void *address, size_t count);
>
>> };
>
>> So in theory one has to implement the two undefined functions.
>
>> For each primitive data type, int, float, etc. or any type designated
>> as primitive define a "load" template for function to read them from the
>> file.
>
>> For each data type that you want to treat specially - rather than
>> allowing the serialization library to do the job - define an overload
>> for operator.
> Just a quick question: what should the default load (I mean
> template<class T>> void load(T & t);) function do? Do I guess correctly
> that it should never be called and is thus undefined to cause link-time
> errors?
It should handle all primitives not otherwise handled specifically. For
example the default load for text archives resolves to input_stream >> t
While for binary archives it resolves to load_binary(sizeof(t), t).
> Looking through the documentation I find references to virtual
> functions:
And?
>> class trivial_iarchive
>> // all input archives must be derived from this base class. This base
>> // class defines the virtual functions necessary for the serialization
>> // library to handle special types for the serialization system.
> I guess that these are incorrect comments left over from an old version?
Correct.
Robert Ramey