4 ms·

The reason is header files. If you do `using namespace std::something` in one file and it gets included in another, the other file now has std::something in the

• jeroenhd 4y ago
  I see, but that's only a program in header files, isn't it? Most code will end up in .cpp files which don't get included (usually). It makes sense to use std::vector in a .h(pp) file, but in the .cpp you should be able to `using namespace std`, right?
  • chongli 4y ago
    Most code will end up in .cpp files which don't get included (usually). Not if a lot of your code is in the form of templates. You have to put those in headers.
    • dcow 4y ago
      At this point, just use a modern language already d=
    • pjmlp 4y ago
      Not when using modules.
• titzer 4y ago
  The word "antiquated" comes to mind, but it's worse than that. An age-old self-created fractal hell of dumb problems created by a simplistic view of code reuse based on the simple mechanism of text inclusion that constantly restrains future evolution. It's antediluvian and just plain backwards.
  • twic 4y ago
    We are at least getting modules real soon now: https://en.cppreference.com/w/cpp/language/modules https://en.cppreference.com/w/cpp/language/modules
    • xigoi 4y ago
      We've been getting them real soon for… about 5 years now?
      • ninkendo 4y ago
        They were supposed to be part of C++11, back when it was called C++0x, before getting punted. So more like almost 20 years now (since some time after C++03.)
        • pjmlp 4y ago
          Java is still trying to get value types. Some things take time when trying to avoid Python 2 / 3 scenarios.
          • xigoi 4y ago
            The Python 2/3 scenario was because of breaking backward compatibility, which is not the case for C++ modules.
    • duped 4y ago
      The only compiler that seems to care about implementing modules is MSVC. It'll be "real soon" when GCC stops crashing.
      • mardifoufs 4y ago
        I think there's a GCC branch that implements module, and it seemed pretty stable. But there must be a reason why it's not merged yet so you're most likely right.
• tragomaskhalos 4y ago
  Using in a header file => complete no-no. Using in a cpp file => absolutely fine.
  • jcelerier 4y ago
    > Using in a cpp file => absolutely fine. definitely not as soon as you want to do unity/jumbo builds (which are in my experience the n°1 thing to do to get fast CI builds)
• lenkite 4y ago
  It should be completely fine to use `using namespace std` inside a function body right ?