"Jonathan Turkanis" wrote:
Here the code for DuckStuffedWithPork needs to be written just once. I wouldn't want to have to write separate specializations
class style1_oarchive : public text_archive { }; class style2_oarchive : public text_archive { }; class style3_oarchive : public text_archive { };
template<> void serialize(style1_oarchive &ar, Duck &d){ // .. }
template<> void serialize(style2_oarchive &ar, Duck &d){ // .. }
template<> void serialize(style3_oarchive &ar, Duck &d){ // .. }
Here I have to repeat the commented-out code three times. If you want to vary styles for two or more types independently this leads to a combinatorial explosion.
This could be solved by: class common_style_oarchive : public text_archive {...}; class style1_oarchive : public common_style_oarchive { }; class style2_oarchive : public common_style_oarchive { }; class style3_oarchive : public common_style_oarchive { }; template<> void serialize(common_style_oarchive &ar, Duck &d){ // .. } This should cover typical situations. When more combinations are needed there could be something as: class common_style_oarchive : public text_archive {...}; class style1_oarchive : public common_style_oarchive { }; class style2_oarchive : public common_style_oarchive { }; class style3_oarchive : public common_style_oarchive { }; template<Archive> void serialize(common_style_oarchive&, Duck& d) { // .... } template<> void serialize(style1_oarchive &ar, Duck &d){ // switch temporarily style for Duck or whatever style_changer_raii_like<Duck> changer(ar, "......"); serialize<common_style_oarchive>(ar, d); } template<> void serialize(style2_oarchive &ar, Duck &d){ style_changer_raii_like<Duck> changer(ar, "......"); serialize<common_style_oarchive>(ar, d); } template<> void serialize(style3_oarchive &ar, Duck &d){ style_changer_raii_like<Duck> changer(ar, "......"); serialize<common_style_oarchive>(ar, d); } Would this be enough to keep code bloat down? /Pavel