Wrap all external libs in namespace (was Consider wrapping rapidjson in a container namespace)

[Iced-Sun]

Because both cereal and rapidjson are header-only and cereal contains a copy of a particular version of rapidjson, it will be conflicted if a project includes them both, unless the versions of rapidjson happen to be the same.

[AzothAmmo]

Seems like a very reasonable thing for us to do. Will also apply to other external libs.

[c42f]

+1 for this - I have a project containing both rapidxml and rapidjson as existing dependencies.

What is the preferred implementation? One option would be to go through rapidjson and wrap all occurrences of namespace rapidjson with

RAPIDJSON_WRAP_NAMESPACE_ENTER
namespace rapidjson {

// ...

} // namespace rapidjson
RAPIDJSON_WRAP_NAMESPACE_EXIT

In rapidjson.h:

#ifdef RAPIDJSON_WRAPPER_NAMESPACE
#   define RAPIDJSON_WRAP_NAMESPACE_ENTER namespace RAPIDJSON_WRAPPER_NAMESPACE {
#   define RAPIDJSON_WRAP_NAMESPACE_EXIT }
#else
#   define RAPIDJSON_WRAP_NAMESPACE_ENTER
#   define RAPIDJSON_WRAP_NAMESPACE_EXIT
#endif

This is potentially something that could be submitted to rapidjson upstream rather than being a cereal-specific hack. Usage in cereal as follows:

#define RAPIDJSON_WRAPPER_NAMESPACE cereal
#include <cereal/external/rapidjson/prettywriter.h>
#include <cereal/external/rapidjson/genericstream.h>
// ...
#undef RAPIDJSON_WRAPPER_NAMESPACE

[AzothAmmo]

Until we upgrade rapidjson/xml to newer versions I'm implementing a quick fix to this by shoving CEREAL_ on the preprocessor stuff and throwing everything else in the cereal namespace.