I never tried with complicated structures, but as far as I know, we can simply do something like:

namespace boost::ublas

{

   bla bla bla...

}

namespace boost::numeric::ublas

{
     using namespace boost::ublas;

}

I just wonder why none of gcc and clang complain about that. I'm obviously missing something because the recursion should be infinite,shouldn't it? https://en.cppreference.com/w/cpp/language/namespace#Using-directives

There is no recursion, as far as I can see, just an alias.

But yes, something like that could work. In fact, I suppose we should start from the opposite end: introduce

so users can start using boost::ublas::...

Then we can incrementally substitute the original code to rid ourselves from boost::numeric.

-- 

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