Question

I think most C++ programmers here would agree that polluting the global namespace is a bad idea, but are there times when this rule can be ignored?

For example, I have a type that I need to use all over a particular application – should I define it thus:

mytypes.h  typedef int MY_TYPE;  foo.cpp  MY_TYPE myType; 

Or use a namespace:

mytypes.h  namespace ns { typedef int MY_TYPE; }  foo.cpp  ns::MY_TYPE myType; ... using namespace ns; MY_TYPE myType; 

Which do you prefer? Are there times when it is acceptable to use the first method?

Answer 1

I use namespaces for partitioning library code from application-specific code, and in a big project to partition the various modules that make up the project.

The global namespace is thus useful for application-specific types and functions that are used across multiple modules in the application.

So, if your MY_TYPE is used throughout your application, put it in the global namespace, otherwise put it in a named namespace.