Do you prefer explicit namespaces or 'using' in C++?

Question

When using C++ namespaces, do you prefer to explicitly name them, like this:

std::cout << \"Hello, world!\\n\";

Or do you prefer

Answer 1

Extra typing is not the issue here. The problem with explicitly qualified names is the visual clutter. Let's face it, C++ syntax is untidy. No need to make this worse by needlessly making names longer and sprinkling the code generously with ::s.

I'm with Jeff Atwood: The Best Code is No Code At All. This is so true.

Namespace imports are a great way of reducing clutter with no drawback: As long as the scope of opened namespaces is reduced to a single compilation unit¹, name conflicts, should they appear, can be resolved easily.

Why explicit names should (in general) be more readable has always been a mystery to me. The readers should generally know the code good enough to be able to deduce semantics. If they aren't, the code needs fixing anyway.

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¹⁾ Corollary: no using in headers!