From 3b8b6d55e0d20f061b901cd512493fa00bf6d1d2 Mon Sep 17 00:00:00 2001
From: jfkirk <james.f.kirk@gmail.com>
Date: Thu, 2 Jun 2016 09:25:43 -0400
Subject: [PATCH] STY: Cleans up ExchangeCalendar construction

---
 zipline/utils/calendars/exchange_calendar.py | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/zipline/utils/calendars/exchange_calendar.py b/zipline/utils/calendars/exchange_calendar.py
index 5464baf3..1e01ed4d 100644
--- a/zipline/utils/calendars/exchange_calendar.py
+++ b/zipline/utils/calendars/exchange_calendar.py
@@ -464,8 +464,6 @@ class ExchangeCalendar(with_metaclass(ABCMeta)):
 
 _static_calendars = {}
 
-_lazy_calendar_names = ['NYSE', 'CME', 'BMF', 'LSE', 'TSX']
-
 
 def get_calendar(name):
     """
@@ -478,41 +476,42 @@ def get_calendar(name):
     """
     # First, check if the calendar is already registered
     if name not in _static_calendars:
-        # The calendar is not registered, so check if it is a lazy calendar
-        if name not in _lazy_calendar_names:
-            # It's not a lazy calendar, so raise an exception
-            raise InvalidCalendarName(calendar_name=name)
 
+        # Check if it is a lazy calendar. If so, build and register it.
         if name == 'NYSE':
             from zipline.utils.calendars.exchange_calendar_nyse \
                 import NYSEExchangeCalendar
             nyse_cal = NYSEExchangeCalendar()
             register_calendar(nyse_cal)
 
-        if name == 'CME':
+        elif name == 'CME':
             from zipline.utils.calendars.exchange_calendar_cme \
                 import CMEExchangeCalendar
             cme_cal = CMEExchangeCalendar()
             register_calendar(cme_cal)
 
-        if name == 'BMF':
+        elif name == 'BMF':
             from zipline.utils.calendars.exchange_calendar_bmf \
                 import BMFExchangeCalendar
             bmf_cal = BMFExchangeCalendar()
             register_calendar(bmf_cal)
 
-        if name == 'LSE':
+        elif name == 'LSE':
             from zipline.utils.calendars.exchange_calendar_lse \
                 import LSEExchangeCalendar
             lse_cal = LSEExchangeCalendar()
             register_calendar(lse_cal)
 
-        if name == 'TSX':
+        elif name == 'TSX':
             from zipline.utils.calendars.exchange_calendar_tsx \
                 import TSXExchangeCalendar
             tsx_cal = TSXExchangeCalendar()
             register_calendar(tsx_cal)
 
+        else:
+            # It's not a lazy calendar, so raise an exception
+            raise InvalidCalendarName(calendar_name=name)
+
     return _static_calendars[name]