From d1592edb29b12dafe5c0d0698310b98b4915cf26 Mon Sep 17 00:00:00 2001
From: Vivien Maisonneuve <v.maisonneuve@gmail.com>
Date: Tue, 19 Aug 2014 16:26:24 +0200
Subject: [PATCH] Cleaner implementation of Domain.__and__()

---
 linpy/domains.py | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/linpy/domains.py b/linpy/domains.py
index 7015252..da0ea97 100644
--- a/linpy/domains.py
+++ b/linpy/domains.py
@@ -320,17 +320,19 @@ class Domain(GeometricObject):
         Return the intersection of two or more domains as a new domain. As an
         alternative, function And() can be used.
         """
-        if len(others) == 0:
-            return self
-        symbols = self._xsymbols((self,) + others)
-        islset1 = self._toislset(self.polyhedra, symbols)
+        result = self
         for other in others:
-            islset2 = other._toislset(other.polyhedra, symbols)
-            islset1 = libisl.isl_set_intersect(islset1, islset2)
-        return self._fromislset(islset1, symbols)
+            result &= other
+        return result
 
     def __and__(self, other):
-        return self.intersection(other)
+        if isinstance(other, Domain):
+            symbols = self._xsymbols([self, other])
+            islset1 = self._toislset(self.polyhedra, symbols)
+            islset2 = other._toislset(other.polyhedra, symbols)
+            islset = libisl.isl_set_intersect(islset1, islset2)
+            return self._fromislset(islset, symbols)
+        return NotImplemented
     __and__.__doc__ = intersection.__doc__
 
     def union(self, *others):
-- 
2.20.1