Don't import pytz unless and until it is needed

efiring · efiring · commit a241e6efcaa4 · 2010-04-05T18:46:18.000Z
svn path=/trunk/matplotlib/; revision=8222
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,3 +1,6 @@
+2010-04-05 Speed up import: import pytz only if and when it is
+           needed.  It is not needed if the rc timezone is UTC. - EF
+
 2010-04-03 Added color kwarg to Axes.hist(), based on work by
            Jeff Klukas. - EF
 
diff --git a/examples/pylab_examples/finance_demo.py b/examples/pylab_examples/finance_demo.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 from pylab import *
 from matplotlib.dates import  DateFormatter, WeekdayLocator, HourLocator, \
-     DayLocator, MONDAY, timezone
+     DayLocator, MONDAY
 from matplotlib.finance import quotes_historical_yahoo, candlestick,\
      plot_day_summary, candlestick2
 
diff --git a/lib/matplotlib/config/cutils.py b/lib/matplotlib/config/cutils.py
@@ -4,7 +4,6 @@
 
 # Stdlib imports
 import os
-import pytz
 import sys
 import tempfile
 import warnings
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
@@ -92,23 +92,13 @@
 """
 import re, time, math, datetime
 
-import pytz
-
-# compatability for 2008c and older versions
-try:
-   import pytz.zoneinfo
-except ImportError:
-   pytz.zoneinfo = pytz.tzinfo
-   pytz.zoneinfo.UTC = pytz.UTC
-
 import matplotlib
 import numpy as np
 
 import matplotlib.units as units
 import matplotlib.cbook as cbook
 import matplotlib.ticker as ticker
 
-from pytz import timezone
 from dateutil.rrule import rrule, MO, TU, WE, TH, FR, SA, SU, YEARLY, \
      MONTHLY, WEEKLY, DAILY, HOURLY, MINUTELY, SECONDLY
 from dateutil.relativedelta import relativedelta
@@ -127,11 +117,28 @@
             'seconds', 'minutes', 'hours', 'weeks')
 
 
+# Make a simple UTC instance so we don't always have to import
+# pytz.  From the python datetime library docs:
+
+class _UTC(datetime.tzinfo):
+    """UTC"""
+
+    def utcoffset(self, dt):
+        return datetime.timedelta(0)
+
+    def tzname(self, dt):
+        return "UTC"
+
+    def dst(self, dt):
+        return datetime.timedelta(0)
 
-UTC = pytz.timezone('UTC')
+UTC = _UTC()
 
 def _get_rc_timezone():
     s = matplotlib.rcParams['timezone']
+    if s == 'UTC':
+        return UTC
+    import pytz
     return pytz.timezone(s)
 
 
