PrologEngine: disable autoload

Turns out unix:dup/2 exists and is autoloaded if the student solution
for dup/2 does not contain the predicate with this name; this can mess
up subsequent tests.

1 files changed, 7 insertions, 1 deletions

diff --git a/prolog/engine.py b/prolog/engine.py
index f94a6ab..26215f8 100644
--- a/prolog/engine.py
+++ b/prolog/engine.py
@@ -89,13 +89,19 @@ class PrologEngine(object):
             'message_to_string/2': PL_predicate(b'message_to_string', 2, None),
             'read_term_from_atom/3': PL_predicate(b'read_term_from_atom', 3, None),
             'safe_goal/1': PL_predicate(b'safe_goal', 1, None),
-            'set_prolog_stack/2': PL_predicate(b'set_prolog_stack', 2, None)
+            'set_prolog_flag/2': PL_predicate(b'set_prolog_flag', 2, None),
+            'set_prolog_stack/2': PL_predicate(b'set_prolog_stack', 2, None),
+            'use_module/1': PL_predicate(b'use_module', 1, None)
         }
         self.err_flags = PL_Q_NODEBUG|PL_Q_CATCH_EXCEPTION
 
         # Load the sandbox and compatibility library.
         self.call('consult/1', [Term(Atom('prolog/lib.pl'))])
 
+        # Load the time module (for call_with_time_limit) then disable autoload.
+        self.call('use_module/1', [Term('library(time)')])
+        self.call('set_prolog_flag/2', [Term('autoload'), Term('false')])
+
         # Increase memory limits.
         self.call('set_prolog_stack/2', [Term('global'), Term('limit(2*10**9)')])
         self.call('set_prolog_stack/2', [Term('local'), Term('limit(2*10**9)')])