Hello Jiri
I think this won´t be possible since the BO mapper overwrites the class designer (Designer.vb or Designer.cs) file every time you rebuild the mapped classes. The best way I can work around is doing one of these:
1) Setup the Root Namespace at Project property level for the entire BO dll
2) Creating a stand alone BO dll for each Business Logic: eg. YourCompany.YourProduct.BO.Sales.dll, YourCompany,YourProduct.BO.Inventory etc...
3) Wait until you are sure you wont need to map the classes anymore (at least for production release) and apply your namespace manually.
Hope this help and I´m pretty sure the experts will add comments too.
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I would like to change the world, but they don´t give me the source code.
MS Windows 7 Ultimate 64-Bit
Intel(R) Core(TM)2 Quad CPU Q9300 2.50 GHz
6.00 GB of RAM, NVIDIA GeForce 9800 GT
MacBook Pro i5 OSX Lion