TestForSTDNamespace

This module checks whether the CXX compiler supports the std namespace for the C++ Standard Library.

Load this module in a CMake project with:

include(TestForSTDNamespace)

Early versions of C++ (pre-C++98) did not have a requirement for a dedicated namespace of C++ Standard Template Library (STL) components (e.g. list, etc.) and other parts of the C++ Standard Library (such as I/O streams cout, endl, etc), so they were available globally.

This module defines the following cache variable:

CMAKE_NO_STD_NAMESPACE

A cache variable containing the result of the check. It will be set to value 0 if the std namespace is supported (C++ 98 and newer), and to value 1 if not (ANSI C++).

备注

The std namespace got formally introduced in C++ 98 standard, making this issue obsolete.

Examples

Including this module will check for the std namespace support and define the CMAKE_NO_STD_NAMESPACE cache variable:

CMakeLists.txt
include(TestForSTDNamespace)
file(
  CONFIGURE
  OUTPUT config.h
  CONTENT "#cmakedefine CMAKE_NO_STD_NAMESPACE"
)

which can be then used in a C++ program to define the missing namespace:

example.cxx
#include "config.h"

#ifdef CMAKE_NO_STD_NAMESPACE
#  define std
#endif

See Also