Merge pull request #100 from pauleve/master

Fix dual for _TRUE and _FALSE

Author: pombredanne

boolean/boolean.py

@@ -838,6 +838,9 @@ def __str__(self):
     def __repr__(self):
         return 'TRUE'
 
+    def __call__(self):
+        return self
+
     __nonzero__ = __bool__ = lambda s: True
 
 
@@ -863,6 +866,9 @@ def __str__(self):
     def __repr__(self):
         return 'FALSE'
 
+    def __call__(self):
+        return self
+
     __nonzero__ = __bool__ = lambda s: False
 
 

boolean/test_boolean.py

@@ -606,6 +606,10 @@ def test_demorgan(self):
         self.assertEqual((~ ~ ~(a & b | c)).demorgan(), ~(a & b) & ~c)
         self.assertEqual(algebra.parse('~' * 10 + '(a&b|c)').demorgan(), a & b | c)
         self.assertEqual(algebra.parse('~' * 11 + '(a&b|c)').demorgan(), (~(a & b | c)).demorgan())
+        _0 = algebra.FALSE
+        _1 = algebra.TRUE
+        self.assertEqual((~(_0)).demorgan(), _1)
+        self.assertEqual((~(_1)).demorgan(), _0)
 
     def test_order(self):
         algebra = BooleanAlgebra()