|Did you know ...||Search Documentation:|
|Dynamic importing using import modules|
Until now we discussed the public module interface that is, at least to some extent, portable between Prolog implementations with a module system that is derived from Quintus Prolog. The remainder of this chapter describes the underlying mechanisms that can be used to emulate other module systems or implement other code-reuse mechanisms.
In addition to built-in predicates, imported predicates and locally
defined predicates, SWI-Prolog modules can also call predicates from its
import modules. Each module has a (possibly empty) list of
import modules. In the default setup, each new module has a single
import module, which is
user for all normal user modules
system for all system library modules. Module
system where all built-in predicates reside.
These special modules are described in more detail in section
In general, the import relations between modules form an acyclic directed graph. The import relation affects the following mechanisms:
systemmodules (in that order).
system. The user may define operators in
userto make them globally visible for compatibility with e.g., SICStus Prolog that has no local operators. Normally operators are defined in a module and, when applicable, exported using the module/2 module header.
The list of import modules for a specific module can be manipulated and queried using the following predicates, as well as using set_module/1.
user, which imports from
system. The predicates add_import_module/3 and delete_import_module/2 can be used to manipulate the import list. See also default_module/2.
enddepending on StartOrEnd. See also import_module/2 and delete_import_module/2.