Initial Commit: help/1 & dir/1

README.md

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+# REPL Help
+
+A couple of utility tools to aid in development by pretty-printing information
+to the REPL.
+
+## Loading
+
+``` logtalk
+{repl_help(loader)}.
+```
+
+## Use
+
+Ensure the JSON library is loaded: `{json(loader)}`.
+
+Find all the predicates for a current object at once:
+
+``` logtalk
+?- dir(json).
+
+[generate/2,parse/2].
+
+true.
+```
+
+Get information about a predicate:
+
+``` logtalk
+?- help(json::generate/2).
+
+:- public(generate/2).
+:- mode(generate(+compound,++term),one_or_error).
+:- info(generate/2, [
+    comment is 'Generates the content using the representation specified in the first argument (``codes(List)``, ``stream(Stream)``, ``file(Path)``, ``chars(List)``, or ``atom(Atom)``) for the term in the second argument. Fails if this term cannot be processed.',
+    argnames is ['Sink','Term']
+]).
+
+true.
+
+```
+
+If you try to get information about an object or predicate that does not exist
+an error will be thrown.

loader.lgt

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+:- initialization((
+	logtalk_load([
+		repl_help
+	], [
+		optimize(on)
+	])
+)).

repl_help.lgt

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+% Predicates for REPL help and information to aid development.
+
+help(Obj::Predicate/Arity) :-
+	% Print the predicate definitions
+	guard_object_(Obj),
+	guard_predicate_(Obj, Predicate/Arity),
+	functor(Term, Predicate, Arity),
+	ignore(help_(scope, Obj, Term, Predicate, Arity)),
+	ignore(help_(mode, Obj, Term, Predicate, Arity)),
+	ignore(help_(info, Obj, Term, Predicate, Arity)).
+
+dir(Obj) :-
+	% Print out all the current predicates for an Object
+	guard_object_(Obj),
+	findall(Predicate, Obj::current_predicate(Predicate), Predicates),
+	format('~n~q~n~n', [Predicates]).
+
+% Rest of code is private
+%
+% % Guards
+guard_object_(Obj) :-
+	current_object(Obj), !.
+guard_object_(Obj) :-
+	throw(error(existance_error(object, Obj))).
+
+guard_predicate_(Obj, Predicate) :-
+	Obj::current_predicate(Predicate), !.
+guard_predicate_(_Obj, Predicate) :-
+	throw(error(existance_error(predicate_declaration, Predicate))).
+
+% % Help info printers
+help_(scope, Obj, Term, Predicate, Arity) :-
+	relaxed_predicate_property_(Obj, Term, scope(Scope)),
+	format('~n:- ~w(~q/~d).~n', [Scope, Predicate, Arity]).
+help_(mode, Obj, Term, _Predicate, _Arity) :-
+	relaxed_predicate_property_(Obj, Term, mode(Args, Resp)),
+	format(':- ~q.~n', [mode(Args, Resp)]).
+help_(info, Obj, Term, Predicate, Arity) :-
+	relaxed_predicate_property_(Obj, Term, info([Info|Infos])),
+	format(':- info(~q/~d, [~n', [Predicate, Arity]),
+	write_infos_(Infos, Info),
+	format(']).~n~n', []).
+
+% % Make predicate_property/2 fail instead of throw
+relaxed_predicate_property_(Obj, Term, Property) :-
+	catch(
+		Obj::predicate_property(Term, Property),
+		error(domain_error(predicate_property, _Term), _),
+		fail
+	).
+
+% % Write out individual info/2 information
+write_infos_([], Info) :-
+	Info =.. [Functor, Arg],
+	format('    ~q is ~q~n', [Functor, Arg]).
+write_infos_([Next|Rest], Info) :-
+	Info =.. [Functor, Arg],
+	format('    ~q is ~q,~n', [Functor, Arg]),
+	write_infos_(Rest, Next).