2.2  Creating an ECLⁱPS^e context

• Initialisation

ECLⁱPS^e runs as a special thread (we will call it ECLⁱPS^e engine) within your application, maintaining its own execution state. This section is about when and how to initialise it. There are parameters to be applied before initialisation, but these are usually acceptable. These parameters are described in Appendix A.

Although it is useful to think of ECLⁱPS^e as a thread, it is not an operating system thread, but is rather implemented as a set of C functions that maintain some state. This state is the complete execution state of the ECLⁱPS^e engine, its stack of goals, its success and failure continuations and its global stack of all constructed data.

At particular points during its execution ECLⁱPS^e will yield control back to the C level. This is implemented by returning from a function. ECLⁱPS^e can then be restarted from the exact point it left off. This is implemented by a function call.

2.2.1  Initialisation

You initialise ECLⁱPS^e by calling the parameterless function

    int ec_init();

A process should do this just once. ec_init returns 0 on success or -1 if an error occurred. It is possible to influence the initialisation of ECLⁱPS^e by setting initialisation options as described in Appendix A.

None of the functions of the interface work before this initialisation. In particular in C++, if you use static variables which are constructed by calling ECLⁱPS^e functions you must arrange for the initialisation to occur before the constructors are called.