From 381df3534d5723ebe24cde856eb58b6dd4e6b765 Mon Sep 17 00:00:00 2001
From: Richard Frank <rich@quantopian.com>
Date: Fri, 10 May 2013 12:00:43 -0400
Subject: [PATCH] MAINT: Ensure we're not setting the blotter to None.

---
 zipline/algorithm.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/zipline/algorithm.py b/zipline/algorithm.py
index 64d552fc..e4135265 100644
--- a/zipline/algorithm.py
+++ b/zipline/algorithm.py
@@ -120,7 +120,9 @@ class TradingAlgorithm(object):
         if self.sim_params:
             self.sim_params.data_frequency = self.data_frequency
 
-        self.blotter = kwargs.pop('blotter', Blotter())
+        self.blotter = kwargs.pop('blotter', None)
+        if not self.blotter:
+            self.blotter = Blotter()
 
         # an algorithm subclass needs to set initialized to True when
         # it is fully initialized.