The multifile directive

The default action upon loading a file or module is to delete all previous byte-code for predicates defined in the file. If this is not the desired behavior, the user may add to the file a declaration

:- multifile Predicate_List .

where Predicate_List is a list of predicates in functor/arity form. The effect of this declaration is to delete only those clauses of predicate/arity that were defined in the file itself. Issues to remember when using multifile in XSB Version 3.0 are:

• If a predicate p/n is to be defined in more than one file, p/n must be declared as multifile in each file in which it is defined.
• The multifile declaration should be trusted only for static code. Multifile declarations are not supported for code that is dynamically loaded (via load_dyn/[1,2] or load_dync/[1,2]).

Other predicates for loading files are ensure_loaded/[1,2].

ensure_loaded(+FileName)

This predicate checks to see whether the object file for FileName is newer than the source code and header files for FileName, and compiles FileName if not. If FileName is loaded into memory, ensure_loaded/1 does not reload it, unlike consult/1 which will always reload

ensure_loaded/2 is documented in Section 6.13.1.