From dce69fc966bf6a5dc84c77b309bb2377e71c4dff Mon Sep 17 00:00:00 2001
From: Stuart Mitchell <hg@stuartmitchell.com>
Date: Mon, 7 Jan 2013 23:33:35 +1300
Subject: [PATCH] made LpVariable.dj, LpConstraint.pi and LpConstraint.slack
 initialise to None

---
 src/pulp/pulp.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/pulp/pulp.py b/src/pulp/pulp.py
index 2fbbcbb..a64c18d 100755
--- a/src/pulp/pulp.py
+++ b/src/pulp/pulp.py
@@ -251,6 +251,7 @@ class LpVariable(LpElement):
         self.upBound = upBound
         self.cat = cat
         self.varValue = None
+        self.dj = None
         self.init = 0
         #code to add a variable to constraints for column based
         # modelling
@@ -825,6 +826,8 @@ class LpConstraint(LpAffineExpression):
         if rhs is not None:
             self.constant = - rhs
         self.sense = sense
+        self.pi = None
+        self.slack = None
         self.modified = True
 
     def getLb(self):