This section documents the built-in predicates to attach packs.
Predicates for creating, registering and installing packs are provided
by the library library(prolog_pack).
- attach_packs
- Attaches all packs in subdirectories of directories that are accessible
through the file search path (see absolute_file_name/3)
pack. The default for this search path is given below. See
file_search_path/2
for the app_data search path.
user:file_search_path(pack, app_data(pack)).
The default path may be overruled with the environment variable
SWIPL_PACK_PATH. This variable must contain a list of
directories separated by the OS-specific path_sep.
The predicate attach_packs/0
is called on startup of SWI-Prolog.
- attach_packs(+Directory)
- attach_packs(+Directory,
+Options)
- Attach all packs that are subdirectories of Directory.
Directory is translated into a physical directory using
absolute_file_name/3.
This implies it can be a term Alias(SubDir) and the search is
relative to the current source file if Directory is not an
absolute path and these predicates are used as a directive. Defined
options are:
- search(+Where)
- Determines the order in which pack library directories are searched.
Default is to add new packages at the end (
last). Using
first, new packages are added at the start.
- duplicate(+Action)
- Determines what happens if a pack with the same name is already
attached. Default is
warning, which prints a warning and
ignores the new pack. Other options are keep, which is like warning
but operates silently and replace, which detaches the old
pack and attaches the new.
- replace(+Boolean)
- If
true, unregister all packs before registering the new
packs.
The predicate attach_packs/2
can be used to attach packages that are bundled with an application.
With the option replace(true),
attach_packs/2
ensures that the application only relies on bundled packs.
- pack_attach(+PackDir,
+Options)
- Attach a single package in PackDir. PackDir is
expected to contain a file‘pack.pl` with the pack metadata and a‘prolog`
directory. Options processed:
- duplicate(+Action)
- What to do if the same package is already installed in a different
directory. Action is one of
- warning
- Warn and ignore the package.
- keep
- Silently ignore the package.
- replace
- Unregister the existing and insert the new package
- search(+Where)
- Determines the order of searching package library directories. Default
is
last, alternative is first.