When the predicates discussed in this section are invoked, file specifications are treated as relative to the current working directory. While loading code, however, file specifications are treated as relative to the directory containing the file being read in. This has the effect that if one of these predicates is invoked recursively, the file specification of the recursive load is relative to the directory of the enclosing load. See Load Intro, for an introduction to these predicates.
Directives will be executed in order of occurrence. Be aware of
the rules governing relative file specifications, as they could
have an effect on the semantics of directives. Only the
first solution of directives is produced, and variable
bindings are not displayed. Directives that fail or raise
exceptions give rise to warning or error messages, but do not terminate
the load. However, these warning or error messages can be
intercepted by the hook user:portray_message/2, which can
call abort/0 to terminate the load, if that is the desired
behavior.
Predicates loading source code are affected by the
character-conversion mapping, cf. char_conversion/2;
see Term I/O.
Most of the predicates listed below take an argument Files, which is a single file specification or a list of file specifications. Source, object and QL files usually end with a `.pl', `.po' and `.ql' suffix respectively. These suffixes are optional. Each file specification may optionally be prefixed by a module name. The module name specifies where to import the exported predicates of a module-file, or where to store the predicates of a non-module-file. The module is created if it doesn't exist already.
absolute_file_name/3 (see Stream Pred) is used for resolving
the file specifications. The file specification user
is reserved and denotes the standard input stream.
These predicates are available in runtime systems with the following limitations:
discontiguous_warnings, redefine_warnings
and single_var_warnings have no effect.
informational Prolog flag is off by default, suppressing
informational messages.
load_files(:Files)load_files(:Files, +Options)use_module/3, which also returns the name of the loaded
module, or imports a set of predicates from an
existing module. Options is a list of zero or more of
the following:
if(X)true (the default) to always load, or changed to
load only if the file has not yet been loaded or if it has
been modified since it was last loaded. A non-module-file
is not considered to have been previously loaded if it was
loaded into a different module. The file user is
never considered to have been previously loaded.
when(When)always (the default) to always load, or compile_time
to load only if the goal is not in the scope of another
load_files/[1,2] directive occurring in a `.po' or
`.ql' file.
The latter is intended for use when the file only defines
predicates that are needed for proper term or goal
expansion during compilation of other files.
load_type(LoadType)source to load source files only, object to
load object (`.po') files only, ql
(obsolescent) to load `.ql' files only, or
latest (the default) to load any type of file, whichever is
newest. If the file is user, source is forced.
imports(Imports)all (the default) to import all exported
predicates if the file is a module-file, or a list of
predicates to import.
compilation_mode(Mode)compile to translate into compiled code, consult to
translate into static, interpreted code, or
assert_all to translate into dynamic, interpreted
code.
The default is the compilation mode of any ancestor
load_files/[1,2] goal, or compile otherwise. Note
that Mode has no effect when a `.po' or `.ql' file is
loaded, and that it is recommended to use assert_all in
conjunction with load_type(source), to ensure that the source
file will be loaded even in the presence of a `.po' or
`.ql' file.
wcx(Wcx)consult(:Files)reconsult(:Files) obsolescent[][:File|+Files]load_files(Files,
[load_type(source),compilation_mode(consult)]).
compile(:Files)load_files(Files,
[load_type(source),compilation_mode(compile)]).
load(:Files) obsolescentload_files(Files, [load_type(ql)]).
ensure_loaded(:Files) ISOload_files(Files, [if(changed)]).
use_module(:File)load_files(File, [if(changed)]).
use_module(:File, +Imports)ensure_loaded/1
and imports the predicates in Imports. If any of
these are not public, a warning is issued. Imports may also be set
to the atom all in which case all public predicates
are imported. Same as load_files(File,
[if(changed),imports(Imports)]).
use_module(-Module, :File, +Imports)use_module(+Module, :File, +Imports)use_module(File, Imports) with the addition that
Module is unified with the loaded module.
fcompile(:Files) development,obsolescentsource_file(?File)source_file(:Head,?File)source_file(-Head,?File)require(:PredSpecOrSpecs) development,obsolescentuse_module/2. The file
containing the predicate definitions will be located in the
following way:
user:library_directory/1 are
searched for a file INDEX.pl. This file is taken to contain
relations between all exported predicates of the
module-files in the library directory and its subdirectories. If
an INDEX.pl is not found, require/1 will try to create one
by loading the library package mkindex and calling
make_index:make_library_index(Directory) (see The Prolog Library).
require/1.