ACT++: Building a Concurrent C++ with Actors

ACT++ (Actors in C++) is a concurrent object-oriented language being designed for distributed real-time applications. The language is a hybrid of the actor kernel language and the object-oriented language C++. The concurrency abstraction of ACT++ is derived from the actor model as defined by Agha. This paper discusses our experience in building a concurrent extension of C++ with the concurrency abstraction of the actor model. The current design of ACT++ and its implementation are described. Some problems found in the Agha's actor model are discussed in the context of distributed real-time applications. The use of ACT++ disclosed the difficulty of combining the actor model of concurrency with class inheritance in an object-oriented language.