From d00edbcf04208338512819d2bac7cafa92a408e6 Mon Sep 17 00:00:00 2001
From: Jeremiah Lowin <jlowin@gmail.com>
Date: Sun, 23 Mar 2014 15:44:40 -0400
Subject: [PATCH] BUG: check that self.logger exists

`self.logger` is initialized as `None` and there is no guarantee that
users have set it, so check that it exists before trying to pass
messages to it.
---
 zipline/algorithm.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/zipline/algorithm.py b/zipline/algorithm.py
index 2002abac..56cde705 100644
--- a/zipline/algorithm.py
+++ b/zipline/algorithm.py
@@ -471,7 +471,8 @@ class TradingAlgorithm(object):
             zero_message = "Price of 0 for {psid}; can't infer value".format(
                 psid=sid
             )
-            self.logger.debug(zero_message)
+            if self.logger:
+                self.logger.debug(zero_message)
             # Don't place any order
             return
         else: