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From: Jeremy Pack (rostovpack_at_[hidden])
Date: 2007-05-28 21:27:26

Versioning can be done very simply using the Boost.Extension library. This
will be described in greater detail in the documentation soon, but you can
get a hint as to how it's done from the examples.

For part 2, this can actually be done using RTTI - just dynamic_cast it. But
yes, this could be done using a similar mechanism to the versioning above. A
factory can contain arbitrary information about the class that it makes
loadable. This information could be a version ID, a list of interfaces it
supports, etc.

So yes, this functionality is already available, and yes, it will (soon I
hope) be documented.

For your second question, it would be possible to provide an auxiliary class
that could make this even simpler - we'll take it into consideration.



On 5/9/07, Stephan Diederich <stephan.diederich_at_[hidden]> wrote:
> Hi,
> I've some questions regarding boost.extension which I think is
> currently prepared to review by Mariano Gabriel Consoni as one of the
> SoC Projects.
> We want to use a plugin loading mechanism in one of our projects and
> have some ideas currently not included in the boost.extensions library.
> - Some kind of versioning of interfaces and implementations.
> The idea is to give an interface (whose implementation is loaded as
> an extension) a version, which can be later compared to the version
> of the loaded implementation. As one of boost.extension's goal is NOT
> to modify a class-header to make it loadable, this should possibly be
> an optional feature. Another option would be to give non versioned
> interfaces always version 0 or 1.
> - It would be nice, if the plugin-loader provides functionality to
> "switch" the interface of an instance of an implementation.
> IIRC, the zone object knows, which interfaces are implemented by a
> loadable class. (when the dll is loaded, the export-function
> registers all the possible interfaces of one class to the zone). With
> that information it should be possible to determine if a given
> instance of a loaded class can be casted to another interface. (I
> think that casting has to be done in the loaded extension, as this is
> the only place where the layout it known. )
> Are there any plans to include above mentioned functionality in
> boost.extension?
> Thanks in advance,
> Stephan
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