SWI-Prolog provides a large number of
hooks, mainly to control handling messages, debugging, startup,
shut-down, macro-expansion, etc. Below is a summary of all defined hooks
with an indication of their portability.
- portray/1
Hook into write_term/3
to alter the way terms are printed (ISO).
- message_hook/3
Hook into print_message/2
to alter the way system messages are printed (Quintus/SICStus).
- message_property/2
Hook into print_message/2
that defines prefix, output stream, color, etc.
- library_directory/1
Hook into absolute_file_name/3
to define new library directories (most Prolog systems).
- file_search_path/2
Hook into absolute_file_name/3
to define new search paths (Quintus/SICStus).
- term_expansion/2
Hook into load_files/2
to modify read terms before they are compiled (macro-processing) (most
Prolog systems).
- goal_expansion/2
Same as term_expansion/2
for individual goals (SICStus).
- prolog_load_file/2
Hook into load_files/2
to load other data formats for Prolog sources from `non-file' resources.
The load_files/2
predicate is the ancestor of consult/1, use_module/1,
etc.
- prolog_edit:locate/3
Hook into edit/1
to locate objects (SWI).
- prolog_edit:edit_source/1
Hook into edit/1
to call an internal editor (SWI).
- prolog_edit:edit_command/2
Hook into edit/1
to define the external editor to use (SWI).
- prolog_list_goal/1
Hook into the tracer to list the code associated to a particular goal
(SWI).
- prolog_trace_interception/4
Hook into the tracer to handle trace events (SWI).
- prolog:debug_control_hook/1
Hook in spy/1, nospy/1, nospyall/0
and debugging/0
to extend these control predicates to higher-level libraries.
- prolog:help_hook/1
Hook in help/0, help/1
and apropos/1
to extend the help system.
- resource/3
Define a new resource (not really a hook, but similar) (SWI).
- exception/3
Old attempt to a generic hook mechanism. Handles undefined predicates
(SWI).
- attr_unify_hook/2
Unification hook for attributed variables. Can be defined in any module.
See section 7.1 for details.
