TipcMt Class

The TipcMt class is a C++ interface to the TipcMt-prefix SmartSockets C API function calls. The TipcMt class contains a pointer to the message type (C type T_IPC_MT).

Standard Message Types

A TipcMt object is created by specifying one of the standard message types to the TipcMt constructor. This is accomplished in one of four ways: specifying a C type T_IPC_MT variable, specifying a standard message type number, specifying a standard message type name, or specifying another TipcMt object. For example:

T_IPC_MT mt; 
 
// Get a C type T_IPC_MT using a C API call. 
mt = TipcMtLookup("info"); 
 
// Create TipcMt objects four different ways 
TipcMt mt1(mt); 
TipcMt mt2("info"); 
TipcMt mt3(T_MT_INFO); 
TipcMt mt4(mt1); 

In a similar manner, TipcMsg objects are also constructed by using a TipcMt object, message type number, a message type name, or an initialized C type T_IPC_MT variable. Depending on your needs, it is possible to save an additional step by constructing TipcMsg objects directly from a message type number, a message type name, or an initialized C type T_IPC_MT variable rather than from a constructed TipcMt object.

User-Defined Message Types

An important use of the TipcMt class is creating user-defined message types when a standard message type does not meet your requirements. A user-defined message type is created by calling the appropriate constructor. The resulting TipcMt object is then used in a TipcMsg constructor to create a message of the user-defined type. For example:

#define XYZ_COORD_DATA 1001 
// Create user defined message type. 
TipcMt mt("xyz_coord_data", XYZ_COORD_DATA, "int4 int4 int4"); 

When a TipcMt object goes out of scope, the message type is not destroyed, just the TipcMt object it was managing. A TipcMt object is reconstructed using the user-defined data type. For example:

TipcMt mt("xyz_coord_data"); 

Vacant and Non-Vacant TipcMt Objects

Like the TipcMsg class, the TipcMt class has vacant and non-vacant objects. A vacant TipcMt object is one that does not refer to a C T_IPC_MT variable. A non-vacant TipcMt object does refer to a C T_IPC_MT variable. A vacant object is constructed this way:

TipcMt mt_vacant; 

A vacant TipcMt object is useful for creating and looking up global callbacks. See Global Callbacks for more information on how to create a global callback.

The TipcMt::Destroy() member function leaves a TipcMt object vacant after it calls the C API function TipcMtDestroy(). The TipcMt::Create() member function leaves a TipcMt object vacant whenever it fails. The overloaded TipcMt::Lookup() member functions also leave an object vacant whenever a message type look up fails.

The TipcMt::Vacant() member function can be used to determine if a TipcMt object is vacant or non-vacant.