1. A computer-implemented method for passing a message from a first thread of execution to a second thread of execution, the first thread being adapted to interpret a block of source code, the second thread having a queue for holding S messages, the method comprising: placing a reference to the message in the queue of the second thread without explicitly invoking the inter-process or inter-thread message passing services of the computer's operating system from within the block of source code, wherein the reference is usable by the second thread to access the message.