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#! python
#
# This module implements a special URL handler that allows selecting an
# alternate implementation provided by some backends.
#
# This file is part of pySerial. https://github.com/pyserial/pyserial
# (C) 2015 Chris Liechti <[email protected]>
#
# SPDX-License-Identifier: BSD-3-Clause
#
# URL format: alt://port[?option[=value][&option[=value]]]
# options:
# - class=X used class named X instead of Serial
#
# example:
# use poll based implementation on Posix (Linux):
# python -m serial.tools.miniterm alt:///dev/ttyUSB0?class=PosixPollSerial
from __future__ import absolute_import
try:
import urlparse
except ImportError:
import urllib.parse as urlparse
import serial
def serial_class_for_url(url):
"""extract host and port from an URL string"""
parts = urlparse.urlsplit(url)
if parts.scheme != 'alt':
raise serial.SerialException(
'expected a string in the form "alt://port[?option[=value][&option[=value]]]": '
'not starting with alt:// ({!r})'.format(parts.scheme))
class_name = 'Serial'
try:
for option, values in urlparse.parse_qs(parts.query, True).items():
if option == 'class':
class_name = values[0]
else:
raise ValueError('unknown option: {!r}'.format(option))
except ValueError as e:
raise serial.SerialException(
'expected a string in the form '
'"alt://port[?option[=value][&option[=value]]]": {!r}'.format(e))
if not hasattr(serial, class_name):
raise ValueError('unknown class: {!r}'.format(class_name))
cls = getattr(serial, class_name)
if not issubclass(cls, serial.Serial):
raise ValueError('class {!r} is not an instance of Serial'.format(class_name))
return (''.join([parts.netloc, parts.path]), cls)
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
if __name__ == '__main__':
s = serial.serial_for_url('alt:///dev/ttyS0?class=PosixPollSerial')
print(s)
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