v2_0_cpp_versioning

API versioning on C++

msgpack-c have introduced API versioning mechanism.

Macros

MSGPACK_DEFAULT_API_VERSION

MSGPACK_DEFAULT_API_VERSION means the default version of msgpack-c API. The current value is 2.

#if !defined(MSGPACK_DEFAULT_API_VERSION)
#define MSGPACK_DEFAULT_API_VERSION 2
#endif

When you want to set MSGPACK_API_VERSION explicitly, give the macro value as follows:

g++ -DMSGPACK_API_VERSION=1

If you set MSGPACK_API_VERSION to 1, the API is compatible to version 1.4.x.

MSGPACK_DEFAULT_API_NS

MSGPACK_DEFAULT_API_NS is a namespace name of the default msgpack version. It names 'v' + MSGPACK_DEFAULT_API_VERSION. e.g.) v1, v2, ...

It is used when you declare and define your custom overloads of operators.

See the following example:

https://github.com/msgpack/msgpack-c/blob/cpp_master/example/cpp03/class_non_intrusive.cpp#L47

MSGPACK_API_VERSION_NAMESPACE

MSGPACK_API_VERSION_NAMESPACE is a function style macro. It defines a namespace. You can pass an argument as the namespace you want to define.

MSGPACK_API_VERSION_NAMESPACE(v1) {
   // ...
}

MSGPACK_API_VERSION_NAMESPACE(v2) {
   // ...
}

The macro is expanded to namespace. If the given namespace name is same as MSGPACK_DEFAULT_API_NS, the macro is expanded as follows:

In the case MSGPACK_DEFAULT_API_NS == v2

C++11

namespace v1 {
   // ...
}

inline namespace v2 {
   // ...
}

C++03

namespace v1 {
   // ...
}

namespace v2{}; using namespace v2; namespace v2 {
   // ...
}

MSGPACK_NULLPTR

If compiler setting is C++/CLI, then MSGPACK_NULLPTR is defined as __nullptr, otherwise nullptr. msgpack-c supports standard C++, C++/CLI is not a standard C++, but we support is as much as we can do. When you write a pull request, plase use MSGPACK_NULLPTR as null pointer.