make compatible with clingo 5.4

telingo/theory/body.py

@@ -4,6 +4,7 @@
 """
 
 import clingo as _clingo
+from telingo.util import getattr_
 
 from .formula import *
 
@@ -456,7 +457,9 @@ def do_translate(self, ctx, step, data):
                 data.done = True
             else:
                 data.literal = ctx.backend.add_atom()
-                ctx.backend.add_external(data.literal, _clingo.TruthValue._True if self.__weak else _clingo.TruthValue._False)
+                true = getattr_(_clingo.TruthValue, "_True", "True_", "True")
+                false = getattr_(_clingo.TruthValue, "_False", "False_", "False")
+                ctx.backend.add_external(data.literal, true if self.__weak else false)
                 ctx.add_todo(self, step)
                 data.done = False
         elif not data.done:

telingo/util.py

@@ -0,0 +1,15 @@
+"""
+This module contains simple helper functions.
+"""
+
+def getattr_(obj, *attrs):
+    """
+    Returns the first attribute of the given object that is available.
+    """
+    for attr in attrs:
+        if hasattr(obj, attr):
+            return getattr(obj, attr)
+    raise AttributeError(
+        '{} does not have any of the attributes {}'.format(
+            obj.__class__.name,
+            ','.join(('"{}"'.format(attr) for attr in attrs))))