Foundation classes - it is impossible avoid "using namespace std" directive when use OCC

In this case there is follow problems.

1. There is dependecies from order of included header files.

2. There is possibility of name conflict with different from std namespaces.

In other words, definition of using some namespace directive must be inside
other namespace or take place in source code, not header files.
 
I suggest to solve the problem like is written in
Bjarne Straustrap"The C++ programming languige", 3-th edition, in [network address removed] paragraf