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Takatoshi Kondo edited this page Feb 13, 2017 · 4 revisions


What is msgpack::object

msgpack::object is a kind of variant type. The internal type of the msgpack::object is corresponding to the msgpack format. Here is the list of types.

MessagePack type msgpack-c type
nil msgpack::type::NIL
boolean msgpack::type::BOOLEAN
uint msgpack::type::POSITIVE_INTEGER
int msgpack::type::NEGATIVE_INTEGER
float 32 msgpack::type::FLOAT32
float 64 msgpack::type::FLOAT64
str msgpack::type::STR
bin msgpack::type::BIN
ext msgpack::type::EXT
array msgpack::type::ARRAY
map msgpack::type::MAP

You can get the type of msgpack::object via type member variable.

If the type of msgpack::object is array or map, the object has children. So msgpack::object is a composite structure.


When the type of msgpack::object is str, bin, or ext, the msgpack::object might have a reference of external memory.


When you use msgpack::unpacker, msgpack::object_handle manages all allocated memories. Treat msgpack::object_handle as a smart pointer.

When you use msgpack::unpack() function without unpack_referenc_func, msgpack::object_handle manages all allocated memories. If you give a custom unpack_referenc_func that returns true, you need to keep the lifetime of the data that you passed to msgpack::unpack() while the unpacked msgpack::object_handle exists.



When you unpack msgpack format data, you get msgpack::object from msgpack::object_handle. Then you get various types values from msgpack::object. If you want to convert to custom types from msgpack::object, see adaptor.

You can create a msgpack::object from a various type value using the following constructor. If you want to create a msgpack::object from a custom type, see and

    template <typename T>
    object(const T& v, zone& z);

You need pass a zone. When the object contains array and/or map, child objects are allocated in the zone. A value that has the type corresponding to str and bin, the contents of the value is copied to the zone with one exception. The exception is msgpack::type::raw_ref. When you call msgpack::object constructor with raw_ref as follows:

msgpack::object obj(msgpack::type::raw_ref(data, size), zone);

The data is NOT copied to the zone.