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Wu Yinghui, Freddie wrote:

[snip]

...

The situation is like this: In the pseudo-code you provided, DoWork() function is declared in the Base class, and is overridden by Derived1 and Derived2, with a fixed number of arguments. My problems is that, my base class cannot predict the exact number of parameters that a derived class may have. (A derived class may have 10 parameters, while another may have none.) So it looks a little bit out-of-shape in terms of the OO programming style I'm familiar with if I'm going to provide overloads of DoWork() for all the possible parameters used by all derived classes (not to mention the undesirable dependency introduced).

In order to know which parameters to send through the interface, you'll have to know the exact subclass? Sorry, that doesn't make sense.

What's the real problem you are trying to solve - could Boost.Variant + static_visitor (or some other variant on the Visitor pattern) help?

/ Johan

My situation is like this: I have a class hierarchy briefly shown as below (assuming virtual member function template is allowed, just to demonstrate the idea): ===== CODE ===== class Base { //... // This is the function that makes use of Boost.Parameter template <typename ArgumentPack> virtual void Configure(ArgumentPack const &arguments) = 0; }; // This class resides in Derived1.dll class Derived1 : public Base { template <typename ArgumentPack> void Configure(ArgumentPack const &arguments) { //... } }; // This class resides in Derived2.dll class Derived2 : public Base { template <typename ArgumentPack> void Configure(ArgumentPack const &arguments) { //... } }; ===== CODE ===== To use the class hierarchy, my program loads the DLL requested by user using LoadLibrary() (We're using Windows, but it should be similar to Linux, I suppose), and makes use of the Derived1/Derived2 classes via a pointer to the Base class. Since I have no information about the derived classes when building my main executable (only Base class is known then), I cannot make direct use of Derived1/Derived2 types in my main program. -- Yet, I need a way to provide some arbitrary set of arguments to the derived classes. Hope my explanation clears your doubts. Do you have any suggestion or alternative design in mind? Cheers, Freddie - -- Wu Yinghui, Freddie Research & Development Senior Software Engineer Volume Interactions Pte Ltd 1 Kim Seng Promenade, #12-01 Great World City East Tower Singapore 237994 Tel: +65 62226962 (Ext 216) Fax: +65 62226215 Email: yhwu@volumeinteractions.com URL: http://www.volumeinteractions.com Important: This message is intended for the recipient(s) addressed above. It contains privileged and confidential information. If you are not the intended recipient, please notify the sender immediately by replying to this message and then delete it from your system. You must not read, copy, use, or disseminate this communication in any form. Thank you. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (MingW32) iD8DBQFFQMFlIgDxhB4QTtMRA5JAAJ0fxjjw9IOlBOr+m2ccXD5d0Sh1EwCeKSJs /NhscTXToOeUpTgwsNBNkr8= =Kb9r -----END PGP SIGNATURE-----