Successful software projects do not end with the product’s rollout. In most projects, new versions that are based on their predecessors are periodically released. Moreover, previous versions have to be supported, patched, and adjusted to operate with new operating systems, locales, and hardware. Web browsers, commercial databases, word processors, and multimedia tools are examples of such products. It is often the case that the same development team has to support several versions of the same software product simultaneously. Usually, a considerable amount of software can be shared among different versions of the same product, but each version also has its specific components. Namespace aliases can be used in these cases to switch swiftly from one version to another. Namespace aliases can provide dynamic namespaces; that is, a namespace alias can point at a given time to a namespace of version X and, at another time, it can refer to a different namespace. For example:

 namespace ver_3_11  //16 bit{    class Winsock{/*..*/};  class FileSystem{/*..*/};};namespace ver_95 //32 bit{    class Winsock{/*..*/};  class FileSystem{/*..*/};}int main()//implementing 16 bit release{   namespace current = ver_3_11; // current is an alias of ver_3_11  using current::Winsock;  using current::FileSystem;  FileSystem  fs; // ver_3_11::FileSystem  //...}

In this example, the alias ‘current’ is a symbol that can refer to either ver_3_11 or ver_95. To switch to a different version, you only have to assign a different namespace to ‘current’.