Python 2 compatibility

jkseppan · jkseppan · commit cc071ff17c3e · 2018-01-19T14:50:39.000+02:00
diff --git a/lib/matplotlib/dviread.py b/lib/matplotlib/dviread.py
@@ -48,6 +48,7 @@
 if six.PY3:
     def ord(x):
         return x
+    buffer = memoryview
 
 _log = logging.getLogger(__name__)
 
@@ -1202,7 +1203,9 @@ def __init__(self, filename=None):
         while not ok:
             self.connection = sqlite3.connect(
                 filename, isolation_level="DEFERRED")
-            if _log.isEnabledFor(logging.DEBUG):
+            if (_log.isEnabledFor(logging.DEBUG) and
+                hasattr(self.connection, 'set_trace_callback')):
+                # set_trace_callback is a Python 3 feature
                 def debug_sql(sql):
                     _log.debug(' '.join(sql.splitlines()).strip())
                 self.connection.set_trace_callback(debug_sql)
@@ -1406,7 +1409,7 @@ def dvi_font_sync_metrics(self, dvifont, connection):
             # make the width data very compressible.
             widths = struct.pack('<{}I'.format(len(dvifont.widths)),
                                  *dvifont.widths)
-            widths = zlib.compress(widths, 9)
+            widths = buffer(zlib.compress(widths, 9))
             connection.execute("""
                 INSERT INTO dvi_font_metrics (id, scale, widths)
                 SELECT id, :scale, :widths FROM dvi_font WHERE texname=:texname
