remove bad quotes

README.rst

@@ -59,9 +59,9 @@ The basic usage is:
     from escpos.printer import Usb
 
     """ Seiko Epson Corp. Receipt Printer (EPSON TM-T88III) """
-    p = Usb(0x04b8, 0x0202, 0, profile="TM-T88III")
+    p = Usb(0x04b8, 0x0202, 0, profile='TM-T88III')
-    p.text("Hello World\n")
+    p.text('Hello World\n')
-    p.image("logo.gif")
+    p.image('logo.gif')
     p.barcode('1324354657687', 'EAN13', 64, 2, '', '')
     p.cut()
 

doc/user/usage.rst

@@ -67,7 +67,7 @@ IP by DHCP or you set it manually.
 
 ::
 
-    Epson = printer.Network("192.168.1.99")
+    Epson = printer.Network('192.168.1.99')
 
 Serial printer
 ^^^^^^^^^^^^^^
@@ -81,7 +81,7 @@ to.
 
 ::
 
-    Epson = printer.Serial("/dev/tty0")
+    Epson = printer.Serial('/dev/tty0')
 
 Other printers
 ^^^^^^^^^^^^^^
@@ -93,7 +93,7 @@ passing the device node name.
 
 ::
 
-    Epson = printer.File("/dev/usb/lp1")
+    Epson = printer.File('/dev/usb/lp1')
 
 The default is "/dev/usb/lp0", so if the printer is located on that
 node, then you don't necessary need to pass the node name.
@@ -110,11 +110,11 @@ on a USB interface.
     """ Seiko Epson Corp. Receipt Printer M129 Definitions (EPSON TM-T88IV) """
     Epson = printer.Usb(0x04b8,0x0202)
     # Print text
-    Epson.text("Hello World\n")
+    Epson.text('Hello World\n')
     # Print image
-    Epson.image("logo.gif")
+    Epson.image('logo.gif')
     # Print QR Code
-    Epson.qr("You can readme from your smartphone")
+    Epson.qr('You can readme from your smartphone')
     # Print barcode
     Epson.barcode('1324354657687','EAN13',64,2,'','')
     # Cut paper
@@ -214,7 +214,7 @@ advantage of the fact that `_raw()` accepts binary strings.)
     from escpos import printer
     p = printer.Serial()  # adapt this to your printer model
 
-    file = open("binary-blob.bin", "rb")  # read in the file containing your commands in binary-mode
+    file = open('binary-blob.bin', 'rb')  # read in the file containing your commands in binary-mode
     data = file.read()
     file.close()
 
@@ -273,8 +273,8 @@ This is probably best explained by an example:
    d = Dummy()
 
    # create ESC/POS for the print job, this should go really fast
-   d.text("This is my image:\n")
+   d.text('This is my image:\n')
-   d.image("funny_cat.png")
+   d.image('funny_cat.png')
    d.cut()
 
    # send code to printer

examples/barcodes.py

@@ -2,7 +2,7 @@ from escpos.printer import Usb
 
 
 # Adapt to your needs
-p = Usb(0x0416, 0x5011, profile="POS-5890")
+p = Usb(0x0416, 0x5011, profile='POS-5890')
 
 # Print software and then hardware barcode with the same content
 p.soft_barcode('code39', '123456')

examples/codepage_tables.py

@@ -17,9 +17,9 @@ def main():
 
     for codepage in sys.argv[1:] or ['USA']:
         dummy.set(height=2, width=2)
-        dummy._raw(codepage + "\n\n\n")
+        dummy._raw(codepage + '\n\n\n')
         print_codepage(dummy, codepage)
-        dummy._raw("\n\n")
+        dummy._raw('\n\n')
 
     dummy.cut()
 
@@ -30,22 +30,22 @@ def print_codepage(printer, codepage):
     if codepage.isdigit():
         codepage = int(codepage)
         printer._raw(CODEPAGE_CHANGE + six.int2byte(codepage))
-        printer._raw("after")
+        printer._raw('after')
     else:
         printer.charcode(codepage)
 
-    sep = ""
+    sep = ''
 
     # Table header
     printer.set(font='b')
-    printer._raw("  {}\n".format(sep.join(map(lambda s: hex(s)[2:], range(0, 16)))))
+    printer._raw('  {}\n'.format(sep.join(map(lambda s: hex(s)[2:], range(0, 16)))))
     printer.set()
 
     # The table
     for x in range(0, 16):
         # First column
         printer.set(font='b')
-        printer._raw("{} ".format(hex(x)[2:]))
+        printer._raw('{} '.format(hex(x)[2:]))
         printer.set()
 
         for y in range(0, 16):

examples/qr_code.py

@@ -4,7 +4,7 @@ from escpos.printer import Usb
 
 
 def usage():
-    print("usage: qr_code.py <content>")
+    print('usage: qr_code.py <content>')
 
 
 if __name__ == '__main__':
@@ -15,5 +15,5 @@ if __name__ == '__main__':
     content = sys.argv[1]
 
     # Adapt to your needs
-    p = Usb(0x0416, 0x5011, profile="POS-5890")
+    p = Usb(0x0416, 0x5011, profile='POS-5890')
     p.qr(content, center=True)

examples/software_barcode.py

@@ -2,7 +2,7 @@ from escpos.printer import Usb
 
 
 # Adapt to your needs
-p = Usb(0x0416, 0x5011, profile="POS-5890")
+p = Usb(0x0416, 0x5011, profile='POS-5890')
 
 # Some software barcodes
 p.soft_barcode('code128', 'Hello')

examples/weather.py

@@ -25,22 +25,22 @@ from escpos.printer import Usb
 
 """ Setting up the main pathing """
 this_dir, this_filename = os.path.split(__file__)
-GRAPHICS_PATH = os.path.join(this_dir, "graphics/climacons/")
+GRAPHICS_PATH = os.path.join(this_dir, 'graphics/climacons/')
 
 # Adapt to your needs
-printer = Usb(0x0416, 0x5011, profile="POS-5890")
+printer = Usb(0x0416, 0x5011, profile='POS-5890')
 
 # You can get your API Key on www.darksky.net and register a dev account.
 # Technically you can use any other weather service, of course :)
-API_KEY = "YOUR API KEY"
+API_KEY = 'YOUR API KEY'
 
-LAT = "22.345490"       # Your Location
+LAT = '22.345490'       # Your Location
-LONG = "114.189945"     # Your Location
+LONG = '114.189945'     # Your Location
 
 
 def forecast_icon(idx):
     icon = data['daily']['data'][idx]['icon']
-    image = GRAPHICS_PATH + icon + ".png"
+    image = GRAPHICS_PATH + icon + '.png'
     return image
 
 
@@ -80,23 +80,23 @@ def forecast(idx):
 
 def icon():
     icon = data['currently']['icon']
-    image = GRAPHICS_PATH + icon + ".png"
+    image = GRAPHICS_PATH + icon + '.png'
     return image
 
 
 deg = ' C'      # Degree symbol on thermal printer, need to find a better way to use a proper degree symbol
 
 # if you want Fahrenheit change units= to 'us'
-url = "https://api.darksky.net/forecast/" + API_KEY + "/" + LAT + "," + LONG + \
+url = 'https://api.darksky.net/forecast/' + API_KEY + '/' + LAT + ',' + LONG + \
-    "?exclude=[alerts,minutely,hourly,flags]&units=si"  # change last bit to 'us' for Fahrenheit
+    '?exclude=[alerts,minutely,hourly,flags]&units=si'  # change last bit to 'us' for Fahrenheit
 response = urllib.urlopen(url)
 data = json.loads(response.read())
 
 printer.print_and_feed(n=1)
-printer.control("LF")
+printer.control('LF')
 printer.set(font='a', height=2, align='center', bold=True, double_height=True)
-printer.text("Weather Forecast")
+printer.text('Weather Forecast')
-printer.text("\n")
+printer.text('\n')
 printer.set(align='center')
 
 
@@ -104,7 +104,7 @@ printer.set(align='center')
 printer.set(font='a', height=2, align='center', bold=True, double_height=False)
 printer.text('Current conditions: \n')
 printer.image(icon())
-printer.text("\n")
+printer.text('\n')
 
 printer.set(font='a', height=2, align='left', bold=False, double_height=False)
 temp = data['currently']['temperature']
@@ -124,4 +124,4 @@ printer.text('Forecast: \n')
 forecast(0)
 forecast(1)
 printer.cut()
-printer.control("LF")
+printer.control('LF')

setup.py

@@ -6,7 +6,7 @@ from setuptools import find_packages, setup
 
 
 base_dir = os.path.dirname(__file__)
-src_dir = os.path.join(base_dir, "src")
+src_dir = os.path.join(base_dir, 'src')
 
 # When executing the setup.py, we need to be able to import ourselves, this
 # means that we need to add the src/ directory to the sys.path.
@@ -54,8 +54,8 @@ setup(
         'receipt,',
     ],
     platforms='any',
-    package_dir={"": "src"},
+    package_dir={'': 'src'},
-    packages=find_packages(where="src", exclude=["tests", "tests.*"]),
+    packages=find_packages(where='src', exclude=['tests', 'tests.*']),
     package_data={'': ['COPYING', 'src/escpos/capabilities.json']},
     include_package_data=True,
     classifiers=[

src/escpos/__init__.py

@@ -7,7 +7,7 @@ from __future__ import division
 from __future__ import print_function
 from __future__ import unicode_literals
 
-__all__ = ["constants", "escpos", "exceptions", "printer"]
+__all__ = ['constants', 'escpos', 'exceptions', 'printer']
 
 try:
     from .version import version as __version__  # noqa

src/escpos/cli.py

@@ -550,7 +550,7 @@ def main():
         # print command with args
         getattr(printer, target_command)(**command_arguments)
         if target_command in REQUIRES_NEWLINE:
-            printer.text("\n")
+            printer.text('\n')
     else:
         command_arguments['printer'] = printer
         globals()[target_command](**command_arguments)

src/escpos/escpos.py

@@ -89,7 +89,7 @@ class Escpos(object):
         """
         raise NotImplementedError()
 
-    def image(self, img_source, high_density_vertical=True, high_density_horizontal=True, impl="bitImageRaster",
+    def image(self, img_source, high_density_vertical=True, high_density_horizontal=True, impl='bitImageRaster',
               fragment_height=960, center=False):
         """ Print an image
 
@@ -141,14 +141,14 @@ class Escpos(object):
                            fragment_height=fragment_height)
             return
 
-        if impl == "bitImageRaster":
+        if impl == 'bitImageRaster':
             # GS v 0, raster format bit image
             density_byte = (0 if high_density_horizontal else 1) + (0 if high_density_vertical else 2)
-            header = GS + b"v0" + six.int2byte(density_byte) + self._int_low_high(im.width_bytes, 2) +\
+            header = GS + b'v0' + six.int2byte(density_byte) + self._int_low_high(im.width_bytes, 2) +\
                 self._int_low_high(im.height, 2)
             self._raw(header + im.to_raster_format())
 
-        if impl == "graphics":
+        if impl == 'graphics':
             # GS ( L raster format graphics
             img_header = self._int_low_high(im.width, 2) + self._int_low_high(im.height, 2)
             tone = b'0'
@@ -160,14 +160,14 @@ class Escpos(object):
             self._image_send_graphics_data(b'0', b'p', header + raster_data)
             self._image_send_graphics_data(b'0', b'2', b'')
 
-        if impl == "bitImageColumn":
+        if impl == 'bitImageColumn':
             # ESC *, column format bit image
             density_byte = (1 if high_density_horizontal else 0) + (32 if high_density_vertical else 0)
-            header = ESC + b"*" + six.int2byte(density_byte) + self._int_low_high(im.width, 2)
+            header = ESC + b'*' + six.int2byte(density_byte) + self._int_low_high(im.width, 2)
-            outp = [ESC + b"3" + six.int2byte(16)]  # Adjust line-feed size
+            outp = [ESC + b'3' + six.int2byte(16)]  # Adjust line-feed size
             for blob in im.to_column_format(high_density_vertical):
-                outp.append(header + blob + b"\n")
+                outp.append(header + blob + b'\n')
-            outp.append(ESC + b"2")  # Reset line-feed size
+            outp.append(ESC + b'2')  # Reset line-feed size
             self._raw(b''.join(outp))
 
     def _image_send_graphics_data(self, m, fn, data):
@@ -182,7 +182,7 @@ class Escpos(object):
         self._raw(GS + b'(L' + header + m + fn + data)
 
     def qr(self, content, ec=QR_ECLEVEL_L, size=3, model=QR_MODEL_2,
-           native=False, center=False, impl="bitImageRaster"):
+           native=False, center=False, impl='bitImageRaster'):
         """ Print QR Code for the provided string
 
         :param content: The content of the code. Numeric data will be more efficiently compacted.
@@ -198,18 +198,18 @@ class Escpos(object):
         """
         # Basic validation
         if ec not in [QR_ECLEVEL_L, QR_ECLEVEL_M, QR_ECLEVEL_H, QR_ECLEVEL_Q]:
-            raise ValueError("Invalid error correction level")
+            raise ValueError('Invalid error correction level')
         if not 1 <= size <= 16:
-            raise ValueError("Invalid block size (must be 1-16)")
+            raise ValueError('Invalid block size (must be 1-16)')
         if model not in [QR_MODEL_1, QR_MODEL_2, QR_MICRO]:
-            raise ValueError("Invalid QR model (must be one of QR_MODEL_1, QR_MODEL_2, QR_MICRO)")
+            raise ValueError('Invalid QR model (must be one of QR_MODEL_1, QR_MODEL_2, QR_MICRO)')
-        if content == "":
+        if content == '':
             # Handle edge case by printing nothing.
             return
         if not native:
             # Map ESC/POS error correction levels to python 'qrcode' library constant and render to an image
             if model != QR_MODEL_2:
-                raise ValueError("Invalid QR model for qrlib rendering (must be QR_MODEL_2)")
+                raise ValueError('Invalid QR model for qrlib rendering (must be QR_MODEL_2)')
             python_qr_ec = {
                 QR_ECLEVEL_H: qrcode.constants.ERROR_CORRECT_H,
                 QR_ECLEVEL_L: qrcode.constants.ERROR_CORRECT_L,
@@ -220,7 +220,7 @@ class Escpos(object):
             qr_code.add_data(content)
             qr_code.make(fit=True)
             qr_img = qr_code.make_image()
-            im = qr_img._img.convert("RGB")
+            im = qr_img._img.convert('RGB')
 
             # Convert the RGB image in printable image
             self.text('\n')
@@ -230,7 +230,7 @@ class Escpos(object):
             return
 
         if center:
-            raise NotImplementedError("Centering not implemented for native QR rendering")
+            raise NotImplementedError('Centering not implemented for native QR rendering')
 
         # Native 2D code printing
         cn = b'1'  # Code type for QR code
@@ -253,7 +253,7 @@ class Escpos(object):
         :param m: Modifier/variant for function. Often '0' where used.
         """
         if len(m) > 1 or len(cn) != 1 or len(fn) != 1:
-            raise ValueError("cn and fn must be one byte each.")
+            raise ValueError('cn and fn must be one byte each.')
         header = self._int_low_high(len(data) + len(m) + 2, 2)
         self._raw(GS + b'(k' + header + cn + fn + m + data)
 
@@ -266,16 +266,16 @@ class Escpos(object):
         """
         max_input = (256 << (out_bytes * 8) - 1)
         if not 1 <= out_bytes <= 4:
-            raise ValueError("Can only output 1-4 bytes")
+            raise ValueError('Can only output 1-4 bytes')
         if not 0 <= inp_number <= max_input:
-            raise ValueError("Number too large. Can only output up to {0} in {1} bytes".format(max_input, out_bytes))
+            raise ValueError('Number too large. Can only output up to {0} in {1} bytes'.format(max_input, out_bytes))
         outp = b''
         for _ in range(0, out_bytes):
             outp += six.int2byte(inp_number % 256)
             inp_number //= 256
         return outp
 
-    def charcode(self, code="AUTO"):
+    def charcode(self, code='AUTO'):
         """ Set Character Code Table
 
         Sets the control sequence from ``CHARCODE`` in :py:mod:`escpos.constants` as active. It will be sent with
@@ -285,7 +285,7 @@ class Escpos(object):
         :param code: Name of CharCode
         :raises: :py:exc:`~escpos.exceptions.CharCodeError`
         """
-        if code.upper() == "AUTO":
+        if code.upper() == 'AUTO':
             self.magic.force_encoding(False)
         else:
             self.magic.force_encoding(code)
@@ -316,7 +316,7 @@ class Escpos(object):
         bounds, regex = BARCODE_FORMATS[bc]
         return any(bound[0] <= len(code) <= bound[1] for bound in bounds) and re_match(regex, code)
 
-    def barcode(self, code, bc, height=64, width=3, pos="BELOW", font="A",
+    def barcode(self, code, bc, height=64, width=3, pos='BELOW', font='A',
                 align_ct=True, function_type=None, check=True):
         """ Print Barcode
 
@@ -409,25 +409,25 @@ class Escpos(object):
                 if bc in BARCODE_TYPES['B']:
                     if not self.profile.supports(BARCODE_B):
                         raise BarcodeTypeError((
-                            "Barcode type '{bc} not supported for "
+                            'Barcode type '{bc} not supported for '
-                            "the current printer profile").format(bc=bc))
+                            'the current printer profile').format(bc=bc))
                     function_type = 'B'
                 else:
                     raise BarcodeTypeError((
-                        "Barcode type '{bc} is not valid").format(bc=bc))
+                        'Barcode type '{bc} is not valid').format(bc=bc))
 
         bc_types = BARCODE_TYPES[function_type.upper()]
         if bc.upper() not in bc_types.keys():
             raise BarcodeTypeError((
-                "Barcode '{bc}' not valid for barcode function type "
+                'Barcode '{bc}' not valid for barcode function type '
-                "{function_type}").format(
+                '{function_type}').format(
                     bc=bc,
                     function_type=function_type,
                 ))
 
         if check and not self.check_barcode(bc, code):
             raise BarcodeCodeError((
-                "Barcode '{code}' not in a valid format for type '{bc}'").format(
+                'Barcode '{code}' not in a valid format for type '{bc}'').format(
                 code=code,
                 bc=bc,
             ))
@@ -439,30 +439,30 @@ class Escpos(object):
         if 1 <= height <= 255:
             self._raw(BARCODE_HEIGHT + six.int2byte(height))
         else:
-            raise BarcodeSizeError("height = {height}".format(height=height))
+            raise BarcodeSizeError('height = {height}'.format(height=height))
         # Width
         if 2 <= width <= 6:
             self._raw(BARCODE_WIDTH + six.int2byte(width))
         else:
-            raise BarcodeSizeError("width = {width}".format(width=width))
+            raise BarcodeSizeError('width = {width}'.format(width=width))
         # Font
-        if font.upper() == "B":
+        if font.upper() == 'B':
             self._raw(BARCODE_FONT_B)
         else:  # DEFAULT FONT: A
             self._raw(BARCODE_FONT_A)
         # Position
-        if pos.upper() == "OFF":
+        if pos.upper() == 'OFF':
             self._raw(BARCODE_TXT_OFF)
-        elif pos.upper() == "BOTH":
+        elif pos.upper() == 'BOTH':
             self._raw(BARCODE_TXT_BTH)
-        elif pos.upper() == "ABOVE":
+        elif pos.upper() == 'ABOVE':
             self._raw(BARCODE_TXT_ABV)
         else:  # DEFAULT POSITION: BELOW
             self._raw(BARCODE_TXT_BLW)
 
         self._raw(bc_types[bc.upper()])
 
-        if function_type.upper() == "B":
+        if function_type.upper() == 'B':
             self._raw(six.int2byte(len(code)))
 
         # Print Code
@@ -471,7 +471,7 @@ class Escpos(object):
         else:
             raise BarcodeCodeError()
 
-        if function_type.upper() == "A":
+        if function_type.upper() == 'A':
             self._raw(NUL)
 
     def soft_barcode(self, barcode_type, data, impl='bitImageColumn',
@@ -489,7 +489,7 @@ class Escpos(object):
         barcode_class = barcode.get_barcode_class(barcode_type)
         my_code = barcode_class(data, writer=image_writer)
 
-        with open(os.devnull, "wb") as nullfile:
+        with open(os.devnull, 'wb') as nullfile:
             my_code.write(nullfile, {
                 'module_height': module_height,
                 'module_width': module_width,
@@ -640,12 +640,12 @@ class Escpos(object):
             return
 
         if divisor not in LINESPACING_FUNCS:
-            raise ValueError("divisor must be either 360, 180 or 60")
+            raise ValueError('divisor must be either 360, 180 or 60')
         if (divisor in [360, 180]
                 and (not(0 <= spacing <= 255))):
-            raise ValueError("spacing must be a int between 0 and 255 when divisor is 360 or 180")
+            raise ValueError('spacing must be a int between 0 and 255 when divisor is 360 or 180')
         if divisor == 60 and (not(0 <= spacing <= 85)):
-            raise ValueError("spacing must be a int between 0 and 85 when divisor is 60")
+            raise ValueError('spacing must be a int between 0 and 85 when divisor is 60')
 
         self._raw(LINESPACING_FUNCS[divisor] + six.int2byte(spacing))
 
@@ -671,14 +671,14 @@ class Escpos(object):
 
         mode = mode.upper()
         if mode not in ('FULL', 'PART'):
-            raise ValueError("Mode must be one of ('FULL', 'PART')")
+            raise ValueError('Mode must be one of ('FULL', 'PART')')
 
-        if mode == "PART":
+        if mode == 'PART':
             if self.profile.supports('paperPartCut'):
                 self._raw(PAPER_PART_CUT)
             elif self.profile.supports('paperFullCut'):
                 self._raw(PAPER_FULL_CUT)
-        elif mode == "FULL":
+        elif mode == 'FULL':
             if self.profile.supports('paperFullCut'):
                 self._raw(PAPER_FULL_CUT)
             elif self.profile.supports('paperPartCut'):
@@ -748,11 +748,11 @@ class Escpos(object):
             * SELECT
             * RESET
         """
-        if hw.upper() == "INIT":
+        if hw.upper() == 'INIT':
             self._raw(HW_INIT)
-        elif hw.upper() == "SELECT":
+        elif hw.upper() == 'SELECT':
             self._raw(HW_SELECT)
-        elif hw.upper() == "RESET":
+        elif hw.upper() == 'RESET':
             self._raw(HW_RESET)
         else:  # DEFAULT: DOES NOTHING
             pass
@@ -767,9 +767,9 @@ class Escpos(object):
         """
         if 0 <= n <= 255:
             # ESC d n
-            self._raw(ESC + b"d" + six.int2byte(n))
+            self._raw(ESC + b'd' + six.int2byte(n))
         else:
-            raise ValueError("n must be betwen 0 and 255")
+            raise ValueError('n must be betwen 0 and 255')
 
     def control(self, ctl, count=5, tab_size=8):
         """ Feed control sequences
@@ -787,13 +787,13 @@ class Escpos(object):
         :raises: :py:exc:`~escpos.exceptions.TabPosError`
         """
         # Set position
-        if ctl.upper() == "LF":
+        if ctl.upper() == 'LF':
             self._raw(CTL_LF)
-        elif ctl.upper() == "FF":
+        elif ctl.upper() == 'FF':
             self._raw(CTL_FF)
-        elif ctl.upper() == "CR":
+        elif ctl.upper() == 'CR':
             self._raw(CTL_CR)
-        elif ctl.upper() == "HT":
+        elif ctl.upper() == 'HT':
             if not (0 <= count <= 32 and
                     1 <= tab_size <= 255 and
                     count * tab_size < 256):
@@ -804,7 +804,7 @@ class Escpos(object):
                 for iterator in range(1, count):
                     self._raw(six.int2byte(iterator * tab_size))
                 self._raw(NUL)
-        elif ctl.upper() == "VT":
+        elif ctl.upper() == 'VT':
             self._raw(CTL_VT)
 
     def panel_buttons(self, enable=True):
@@ -930,16 +930,16 @@ class EscposIO(object):
         elif isinstance(text, list) or isinstance(text, tuple):
             lines = text
         else:
-            lines = ["{0}".format(text), ]
+            lines = ['{0}'.format(text), ]
 
         # TODO check unicode handling
         # TODO flush? or on print? (this should prob rather be handled by the _raw-method)
         for line in lines:
             self.printer.set(**params)
             if isinstance(text, six.text_type):
-                self.printer.text(u"{0}\n".format(line))
+                self.printer.text(u'{0}\n'.format(line))
             else:
-                self.printer.text("{0}\n".format(line))
+                self.printer.text('{0}\n'.format(line))
 
     def close(self):
         """ called upon closing the `with`-statement

src/escpos/exceptions.py

@@ -51,13 +51,13 @@ class BarcodeTypeError(Error):
     one of those specified in :py:meth:`escpos.escpos.Escpos.barcode`.
     The returned error code is `10`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 10
 
     def __str__(self):
-        return "No Barcode type is defined ({msg})".format(msg=self.msg)
+        return 'No Barcode type is defined ({msg})'.format(msg=self.msg)
 
 
 class BarcodeSizeError(Error):
@@ -67,13 +67,13 @@ class BarcodeSizeError(Error):
     The size of the barcode has to be in the range that is specified in :py:meth:`escpos.escpos.Escpos.barcode`.
     The resulting returncode is `20`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 20
 
     def __str__(self):
-        return "Barcode size is out of range ({msg})".format(msg=self.msg)
+        return 'Barcode size is out of range ({msg})'.format(msg=self.msg)
 
 
 class BarcodeCodeError(Error):
@@ -83,13 +83,13 @@ class BarcodeCodeError(Error):
     was True and the check failed.
     The returncode for this exception is `30`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 30
 
     def __str__(self):
-        return "No Barcode code was supplied ({msg})".format(msg=self.msg)
+        return 'No Barcode code was supplied ({msg})'.format(msg=self.msg)
 
 
 class ImageSizeError(Error):
@@ -97,7 +97,7 @@ class ImageSizeError(Error):
 
     The returncode for this exception is `40`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 40
@@ -111,13 +111,13 @@ class ImageWidthError(Error):
 
     The return code for this exception is `41`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 41
 
     def __str__(self):
-        return "Image width is too large ({msg})".format(msg=self.msg)
+        return 'Image width is too large ({msg})'.format(msg=self.msg)
 
 
 class TextError(Error):
@@ -126,13 +126,13 @@ class TextError(Error):
     This exception is raised when an empty string is passed to :py:meth:`escpos.escpos.Escpos.text`.
     The returncode for this exception is `50`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 50
 
     def __str__(self):
-        return "Text string must be supplied to the text() method ({msg})".format(msg=self.msg)
+        return 'Text string must be supplied to the text() method ({msg})'.format(msg=self.msg)
 
 
 class CashDrawerError(Error):
@@ -141,13 +141,13 @@ class CashDrawerError(Error):
     A valid pin number has to be passed onto the method :py:meth:`escpos.escpos.Escpos.cashdraw`.
     The returncode for this exception is `60`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 60
 
     def __str__(self):
-        return "Valid pin must be set to send pulse ({msg})".format(msg=self.msg)
+        return 'Valid pin must be set to send pulse ({msg})'.format(msg=self.msg)
 
 
 class TabPosError(Error):
@@ -157,13 +157,13 @@ class TabPosError(Error):
     This exception is raised by :py:meth:`escpos.escpos.Escpos.control`.
     The returncode for this exception is `70`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 70
 
     def __str__(self):
-        return "Valid tab positions must be in the range 0 to 16 ({msg})".format(msg=self.msg)
+        return 'Valid tab positions must be in the range 0 to 16 ({msg})'.format(msg=self.msg)
 
 
 class CharCodeError(Error):
@@ -172,13 +172,13 @@ class CharCodeError(Error):
     The supplied charcode-name in :py:meth:`escpos.escpos.Escpos.charcode` is unknown.
     Ths returncode for this exception is `80`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 80
 
     def __str__(self):
-        return "Valid char code must be set ({msg})".format(msg=self.msg)
+        return 'Valid char code must be set ({msg})'.format(msg=self.msg)
 
 
 class USBNotFoundError(Error):
@@ -187,13 +187,13 @@ class USBNotFoundError(Error):
     The USB device seems to be not plugged in.
     Ths returncode for this exception is `90`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 90
 
     def __str__(self):
-        return "USB device not found ({msg})".format(msg=self.msg)
+        return 'USB device not found ({msg})'.format(msg=self.msg)
 
 
 class SetVariableError(Error):
@@ -202,13 +202,13 @@ class SetVariableError(Error):
     Check set variables against minimum and maximum values
     Ths returncode for this exception is `100`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 100
 
     def __str__(self):
-        return "Set variable out of range ({msg})".format(msg=self.msg)
+        return 'Set variable out of range ({msg})'.format(msg=self.msg)
 
 
 # Configuration errors
@@ -219,13 +219,13 @@ class ConfigNotFoundError(Error):
     The default or passed configuration file could not be read
     Ths returncode for this exception is `200`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 200
 
     def __str__(self):
-        return "Configuration not found ({msg})".format(msg=self.msg)
+        return 'Configuration not found ({msg})'.format(msg=self.msg)
 
 
 class ConfigSyntaxError(Error):
@@ -234,13 +234,13 @@ class ConfigSyntaxError(Error):
     The syntax is incorrect
     Ths returncode for this exception is `210`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 210
 
     def __str__(self):
-        return "Configuration syntax is invalid ({msg})".format(msg=self.msg)
+        return 'Configuration syntax is invalid ({msg})'.format(msg=self.msg)
 
 
 class ConfigSectionMissingError(Error):
@@ -249,10 +249,10 @@ class ConfigSectionMissingError(Error):
     The part of the config asked for doesn't exist in the loaded configuration
     Ths returncode for this exception is `220`.
     """
-    def __init__(self, msg=""):
+    def __init__(self, msg=''):
         Error.__init__(self, msg)
         self.msg = msg
         self.resultcode = 220
 
     def __str__(self):
-        return "Configuration section is missing ({msg})".format(msg=self.msg)
+        return 'Configuration section is missing ({msg})'.format(msg=self.msg)

src/escpos/image.py

@@ -42,14 +42,14 @@ class EscposImage(object):
         # Convert to white RGB background, paste over white background
         # to strip alpha.
         img_original = img_original.convert('RGBA')
-        im = Image.new("RGB", img_original.size, (255, 255, 255))
+        im = Image.new('RGB', img_original.size, (255, 255, 255))
         im.paste(img_original, mask=img_original.split()[3])
         # Convert down to greyscale
-        im = im.convert("L")
+        im = im.convert('L')
         # Invert: Only works on 'L' images
         im = ImageOps.invert(im)
         # Pure black and white
-        self._im = im.convert("1")
+        self._im = im.convert('1')
 
     @property
     def width(self):
@@ -125,7 +125,7 @@ class EscposImage(object):
         old_width, height = self._im.size
         new_size = (max_width, height)
 
-        new_im = Image.new("1", new_size)
+        new_im = Image.new('1', new_size)
         paste_x = int((max_width - old_width) / 2)
 
         new_im.paste(self._im, (paste_x, 0))

src/escpos/katakana.py

@@ -33,7 +33,7 @@ def encode_katakana(text):
             # TODO doesn't this discard all that is not in the map? Can we be sure that the input does contain only
             # encodable characters? We could at least throw an exception if encoding is not possible.
             pass
-    return b"".join(encoded)
+    return b''.join(encoded)
 
 
 TXT_ENC_KATAKANA_MAP = {

src/escpos/magicencode.py

@@ -75,11 +75,11 @@ class Encoder(object):
         """
         codepage = CodePages.get_encoding(encoding)
         if 'data' in codepage:
-            encodable_chars = list("".join(codepage['data']))
+            encodable_chars = list(''.join(codepage['data']))
             assert(len(encodable_chars) == 128)
             return encodable_chars
         elif 'python_encode' in codepage:
-            encodable_chars = [u" "] * 128
+            encodable_chars = [u' '] * 128
             for i in range(0, 128):
                 codepoint = i + 128
                 try:
@@ -280,7 +280,7 @@ class MagicEncode(object):
 
     def write_with_encoding(self, encoding, text):
         if text is not None and type(text) is not six.text_type:
-            raise Error("The supplied text has to be unicode, but is of type {type}.".format(
+            raise Error('The supplied text has to be unicode, but is of type {type}.'.format(
                 type=type(text)
             ))
 

src/escpos/printer.py

@@ -54,7 +54,7 @@ class Usb(Escpos):
         """ Search device on USB tree and set it as escpos device """
         self.device = usb.core.find(idVendor=self.idVendor, idProduct=self.idProduct)
         if self.device is None:
-            raise USBNotFoundError("Device not found or cable not plugged in.")
+            raise USBNotFoundError('Device not found or cable not plugged in.')
 
         check_driver = None
 
@@ -68,13 +68,13 @@ class Usb(Escpos):
                 self.device.detach_kernel_driver(0)
             except usb.core.USBError as e:
                 if check_driver is not None:
-                    print("Could not detatch kernel driver: {0}".format(str(e)))
+                    print('Could not detatch kernel driver: {0}'.format(str(e)))
 
         try:
             self.device.set_configuration()
             self.device.reset()
         except usb.core.USBError as e:
-            print("Could not set configuration: {0}".format(str(e)))
+            print('Could not set configuration: {0}'.format(str(e)))
 
     def _raw(self, msg):
         """ Print any command sent in raw format
@@ -107,7 +107,7 @@ class Serial(Escpos):
 
     """
 
-    def __init__(self, devfile="/dev/ttyS0", baudrate=9600, bytesize=8, timeout=1,
+    def __init__(self, devfile='/dev/ttyS0', baudrate=9600, bytesize=8, timeout=1,
                  parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE,
                  xonxoff=False, dsrdtr=True, *args, **kwargs):
         """
@@ -143,9 +143,9 @@ class Serial(Escpos):
                                     xonxoff=self.xonxoff, dsrdtr=self.dsrdtr)
 
         if self.device is not None:
-            print("Serial printer enabled")
+            print('Serial printer enabled')
         else:
-            print("Unable to open serial printer on: {0}".format(str(self.devfile)))
+            print('Unable to open serial printer on: {0}'.format(str(self.devfile)))
 
     def _raw(self, msg):
         """ Print any command sent in raw format
@@ -209,7 +209,7 @@ class Network(Escpos):
         self.device.connect((self.host, self.port))
 
         if self.device is None:
-            print("Could not open socket for {0}".format(self.host))
+            print('Could not open socket for {0}'.format(self.host))
 
     def _raw(self, msg):
         """ Print any command sent in raw format
@@ -240,7 +240,7 @@ class File(Escpos):
 
     """
 
-    def __init__(self, devfile="/dev/usb/lp0", auto_flush=True, *args, **kwargs):
+    def __init__(self, devfile='/dev/usb/lp0', auto_flush=True, *args, **kwargs):
         """
 
         :param devfile: Device file under dev filesystem
@@ -253,10 +253,10 @@ class File(Escpos):
 
     def open(self):
         """ Open system file """
-        self.device = open(self.devfile, "wb")
+        self.device = open(self.devfile, 'wb')
 
         if self.device is None:
-            print("Could not open the specified file {0}".format(self.devfile))
+            print('Could not open the specified file {0}'.format(self.devfile))
 
     def flush(self):
         """ Flush printing content """