Most of the above assumes Prolog is‘in charge’of the
application and C++ is used to add functionality to Prolog, either for
accessing external resources or for performance reasons. In some
applications, there is a main-program and we want to use Prolog
as a
logic server. For these applications, the class
PlEngine has been defined.
Only a single instance of this class can exist in a process. When
used in a multi-threading application, only one thread at a time may
have a running query on this engine. Applications should ensure this
using proper locking techniques.29For
Unix, there is a multi-threaded version of SWI-Prolog. In this version
each thread can create and destroy a thread-engine. There is currently
no C++ interface defined to access this functionality, though ---of
course--- you can use the C-functions.
- PlEngine :: PlEngine(int argc, char **argv)
- Initialises the Prolog engine. The application should make sure to pass
argv[0]
from its main function, which is needed in the Unix version to find the
running executable. See PL_initialise() for details.
- PlEngine :: PlEngine(char *argv0)
- Simple constructure using the main constructor with the specified
argument for
argv[0].
- ~ PlEngine()
- Calls PL_cleanup() to destroy all data created by the Prolog
engine.
Section 1.4.11 has a simple
example using this class.
