Fix Py2/3 compatibility (#40)

brother_ql/backends/linux_kernel.py

@@ -5,6 +5,9 @@ Backend to support Brother QL-series printers via the linux kernel USB printer i
 Works on Linux.
 """
 
+from __future__ import unicode_literals
+from builtins import str
+
 import glob, os, time, select
 
 from .generic import BrotherQLBackendGeneric

brother_ql/backends/network.py

@@ -5,6 +5,9 @@ Backend to support Brother QL-series printers via network.
 Works cross-platform.
 """
 
+from __future__ import unicode_literals
+from builtins import str
+
 import socket, os, time, select
 
 from .generic import BrotherQLBackendGeneric

brother_ql/backends/pyusb.py

@@ -8,6 +8,9 @@ Requires PyUSB: https://github.com/walac/pyusb/
 Install via `pip install pyusb`
 """
 
+from __future__ import unicode_literals
+from builtins import str
+
 import time
 
 import usb.core

brother_ql/conversion.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 
-from __future__ import division
+from __future__ import division, unicode_literals
+from builtins import str
 
 import logging
 
@@ -12,11 +13,6 @@ from brother_ql.devicedependent import label_type_specs, ENDLESS_LABEL, DIE_CUT_
 from brother_ql import BrotherQLUnsupportedCmd
 from brother_ql.image_trafos import filtered_hsv
 
-try:
-    unicode
-except:
-    unicode = str
-
 logger = logging.getLogger(__name__)
 
 logging.getLogger("PIL.PngImagePlugin").setLevel(logging.WARNING)
@@ -83,7 +79,7 @@ def convert(qlr, images, label,  **kwargs):
     for image in images:
         if isinstance(image, Image.Image):
             im = image
-        elif isinstance(image, (unicode, str)):
+        elif isinstance(image, str):
             im = Image.open(image)
         else:
             raise NotImplementedError("The image argument needs to be an Image() instance or the filename to an image.")