C++ doesn't have a "load this module" statement. I does have an "include all the contents of X file here", and file X has to deal with possible duplication and

C++ doesn't have a "load this module" statement. I does have an "include all the contents of X file here", and file X has to deal with possible duplication and cyclic dependencies, usually with something like #ifndef _SOME_FILE_H #define _SOME_FILE_H // code goes here #endif Also any "module" can define any global variable, so name clashes (esp. with C libraries) are possible. Most languages with proper modules the "global" variables are module-wide. An equally nasty issue happens with JS, where many libraries must be loaded in the proper order and not duplicated. There are a bunch of module systems but none is part of the spec. The good thing is that module systems are easy to make thanks to closures.