Namespaces in Python vs C++

There isn't really an analogue. Consider this simple header:

// a.h
namespace ns {
    struct A { .. };
    struct B { .. };
}

If we were to do this:

#include "a.h"
using ns::A;

The point of that code is to be able to write A unqualified (as opposed to having to write ns::A). Now, you might consider a python equivalent as:

from a import A

But regardless of the using, the entire a.h header will still be included and compiled, so we would still be able to write ns::B, whereas in the Python version, a.B would not be visible.

The more expansive version:

using namespace ns;

definitely has no Python analogue either, since that brings in all names from namespace ns throughout the entire code-base - and namespaces can be reused. The most common thing I see beginner C++ programmers do is:

#include <vector>
#include <map>
#include <algorithm>

using namespace std; // bring in EVERYTHING

That one line is kind of equivalent to:

from vector import *
from map import *
from algorithm import *

at least in what it does, but then it only actually brings in what's in namespace std - which isn't necessarily everything.