SWI-Prolog offers an extensible interface which allows the user to
edit objects of the program: predicates, modules, files, etc. The editor
interface is implemented by edit/1
and consists of three parts:
locating, selecting and starting the editor.
Any of these parts may be customized. See section
4.4.1.
The built-in edit specifications for edit/1
(see prolog_edit:locate/3)
are described in the table below:
| Fully specified objects |
| <Module>:<Name>/<Arity> | Refers
to a predicate |
| module(<Module>) | Refers to a module |
| file(<Path>) | Refers to a file |
| source_file(<Path>) | Refers to a loaded
source file |
| Ambiguous specifications |
| <Name>/<Arity> | Refers
to this predicate in any module |
| <Name> | Refers to (1) the named
predicate in any module with any arity, (2) a (source) file, or (3) a
module. |
- edit(+Specification)
- First, exploit prolog_edit:locate/3
to translate
Specification into a list of Locations. If there is
more than one‘hit’, the user is asked to select from the
locations found. Finally, prolog_edit:edit_source/1
is used to invoke the user's preferred editor. Typically, edit/1
can be handed the name of a predicate, module, basename of a file, XPCE
class, XPCE method, etc.
- edit
- Edit the‘default’file using edit/1.
The default file is either the first
.pl file from the
commandline (the associated file, see the Prolog flag associated_file
or the first script file specified using the -s or -l
command line option. When using the Windows shell while SWI-Prolog is
associated with the .pl extension this is the file loaded
by double-clicking a .pl file. See also section
2.11.1.1.
The predicates described in this section are hooks that can
be defined to disambiguate specifications given to edit/1,
find the related source, and open an editor at the given source
location.
- prolog_edit:locate(+Spec,
-FullSpec, -Location)
- Where Spec is the specification provided through edit/1.
This multifile predicate is used to enumerate locations where an object
satisfying the given Spec can be found. FullSpec
is unified with the complete specification for the object. This
distinction is used to allow for ambiguous specifications. For example,
if Spec is an atom, which appears as the basename of a loaded
file and as the name of a predicate, FullSpec will be bound
to
file(Path) or Name/Arity.
Location is a list of attributes of the location.
Normally, this list will contain the term file(File) and,
if available, the term line(Line).
- prolog_edit:locate(+Spec,
-Location)
- Same as prolog_edit:locate/3,
but only deals with fully specified objects.
- prolog_edit:edit_source(+Location)
- Start editor on Location. See prolog_edit:locate/3
for the format of a location term. This multifile predicate is normally
not defined. If it succeeds, edit/1
assumes the editor is started.
If it fails, edit/1
uses its internal defaults, which are defined by the Prolog flag editor
and/or the environment variable
EDITOR. The following rules apply. If the Prolog flag editor
is of the format $<name>, the editor is
determined by the environment variable <name>. Else, if
this flag is pce_emacs or built_in
and XPCE is loaded or can be loaded, the built-in Emacs clone
is used. Else, if the environment EDITOR is set, this
editor is used. Finally,
vi is used as default on Unix systems and notepad on
Windows.
See the default user preferences file customize/init.pl
for examples.
- prolog_edit:edit_command(+Editor,
-Command)
- Determines how Editor is to be invoked using shell/1. Editor
is the determined editor (see prolog_edit:edit_source/1),
without the full path specification, and without a possible (
.exe)
extension. Command is an atom describing the command. The
following %-sequences are replaced in Command before the
result is handed to shell/1:
| %e | Replaced by the (OS) command name of the editor |
| %f | Replaced by the (OS) full path name of the file |
| %d | Replaced by the line number |
If the editor can deal with starting at a specified line, two clauses
should be provided. The first pattern invokes the editor with a line
number, while the second is used if the line number is unknown.
The default contains definitions for vi, emacs,
emacsclient, vim, notepad^* and
wordpad^*. Starred editors do not provide starting at
a given line number.
Please contribute your specifications to bugs@swi-prolog.org.
- prolog_edit:load
- Normally an undefined multifile predicate. This predicate may be defined
to provide loading hooks for user extensions to the edit module. For
example, XPCE provides the code below to load
library(swi_edit),
containing definitions to locate classes and methods as well as to bind
this package to the PceEmacs built-in editor.
:- multifile prolog_edit:load/0.
prolog_edit:load :-
ensure_loaded(library(swi_edit)).
