Move isl version test in Domain.vertices outside

diff --git a/linpy/domains.py b/linpy/domains.py
index 9fdc7d5..4b3e982 100644 (file)
--- a/linpy/domains.py
+++ b/linpy/domains.py
@@ -391,7 +391,10 @@ class Domain(GeometricObject):
         islset = libisl.isl_set_lexmax(islset)
         return self._fromislset(islset, self.symbols)
 
-    _RE_COORDINATE = re.compile(r'\((?P<num>\-?\d+)\)(/(?P<den>\d+))?')
+    if islhelper.isl_version >= '0.13':
+        _RE_COORDINATE = re.compile(r'\((?P<num>\-?\d+)\)(/(?P<den>\d+))?')
+    else:
+        _RE_COORDINATE = None
 
     def vertices(self):
         """
@@ -409,7 +412,7 @@ class Domain(GeometricObject):
         for vertex in vertices:
             expr = libisl.isl_vertex_get_expr(vertex)
             coordinates = []
-            if islhelper.isl_version < '0.13':
+            if self._RE_COORDINATE is None:
                 constraints = islhelper.isl_basic_set_constraints(expr)
                 for constraint in constraints:
                     constant = libisl.isl_constraint_get_constant_val(constraint)