Data commit

Task/Introspection/Logtalk/introspection.logtalk

@@ -0,0 +1,33 @@
+:- object(my_application).
+
+    :- initialization((
+        check_logtalk_version,
+        compute_predicate_if_available
+    )).
+
+    check_logtalk_version :-
+        % version data is available by consulting the "version_data" flag
+        current_logtalk_flag(version_data, logtalk(Major,Minor,Patch,_)),
+        (   (Major,Minor,Patch) @< (3,0,0) ->
+            write('Logtalk version is too old! Please upgrade to version 3.0.0 or later'), nl,
+            halt
+        ;   true
+        ).
+
+    % Logtalk is not a functional language and thus doesn't support user-defined functions; we
+    % use instead a predicate, abs/2, with a return argument to implement the abs/1 function
+    compute_predicate_if_available :-
+        (   % check that the variable "bloop" is defined within this object
+            current_predicate(bloop/1),
+            % assume that the abs/2 predicate, if available, comes from a "utilities" object
+            utilities::current_predicate(abs/2) ->
+            bloop(Value),
+            utilities::abs(Value, Result),
+            write('Function value: '), write(Result), nl
+        ;   write('Could not compute function!'), nl
+        ).
+
+    % our "bloop" variable value as per task description
+    bloop(-1).
+
+:- end_object.