/*
** $Id: namespaces.cc 824 2008-03-09 19:23:52Z phf $
**
** Examples of namespaces.
*/

// Remember that the iostream stuff is in namespace std!

#include <iostream>

// In C++ we can use namespaces to "partition" the
// identifiers (names) we use into separate "chunks".
// This allows people to use the same identifiers in
// different libraries yet combine those libraries
// in one program. For example, there is a "cout" in
// namespace "std" but we can have something else
// called "cout" in a different namespace, "cs120"
// for example.

namespace cs120 {
  int cout = 47;
}

// We can also "add" identifiers into an existing
// namespace. This is a Bad Idea (tm) if you don't
// "own" the particular namespace. So the following
// example, which adds "blabla" to namespace "std"
// is not something you usually want to do. However,
// for namespaces that you control, it's necessary
// to enable this so that pieces of your namespace
// can be split into different source files.

namespace std {
  int blabla = 30;
}

// We can also have a global definition for "cout" here,
// no conflict with either std::cout or cs120::cout; it's
// in no particular namespace.

char* cout = "Bla!";

// Here comes the main function. :-)

int main()
{
  // And another one, just for kicks...

  int cout = cs120::cout;

  // This "cout" is different from all the other ones we had
  // so far; it's different for sure from the ones in "std"
  // and "cs120" above; it's also different from the global
  // "cout" we defined just a few lines above.

  // This "cout" will "shadow" the outer one, but we can still
  // get to that one using a special notation:

  std::cout << std::cout << std::endl // in std
            << cs120::cout << std::endl // in cs120
            << ::cout << std::endl // the global one
            << cout << std::endl; // the local one

  // Completely arbitrary aside: Note that C++ comes with a bool
  // type already, no need for a separate #include file like we
  // had in C99.

  bool aha = true;

  // And like before, they convert easily...

  cout = aha;
  aha = cout;

  // And let's print them?

  std::cout << cout << std::endl;
  std::cout << aha << std::endl;

  // Everything's okay... :-)
  return 0;
}