A definition of namespace alias can be used to redefine a previously defined namespace alias declared in that scope, as long as the new definition refers only to the same namespace. In other words, you’re allowed to repeat an existing definition of a namespace alias but you cannot change the meaning of a previous namespace alias:
namespace Company_with_very_long_name { /* ... */ }namespace CWVLN=Company_with_very_long_name; // aliasnamespace CWVLN=Company_with_very_long_name;//OK, duplicatenamespace CWVLN=CWVLN; // also OKnamespace CWVLN=std; // errorThis rule enables you to place the same namespace alias definition in every source file of the same project.
