Modern C++ Programming Cookbook

How it works...

When a function is declared in a translation unit, it has external linkage. That means two functions with the same name from two different translation units would generate a linkage error because it is not possible to have two symbols with the same name. The way this problem is solved in C, and by some in C++ also, is to declare the function or variable static and change its linkage from external to internal. In this case, its name is no longer exported outside the translation unit, and the linkage problem is avoided.

The proper solution in C++ is to use unnamed namespaces. When you define a namespace like the ones shown above, the compiler transforms it to the following:

    // file1.cpp     namespace _unique_name_ {}  using namespace ...