For many command line scripts I found that I was writing the same ArgumentParser code over and over again. So I wrote this library to save all of that repeated work.
In some use cases you may want to use a helper multiple times in the one script.
For example, a script that needs to open two serial ports, and you want to configure all the parameters for each port.
To do this you would pass in the shard option and all the parser parameters will be namespaced by the passed in shard
value.
The default value for each cli option can be set with an environment variable of the same name, converted to uppercase
and with '-' replaced with '_'. For example, if shard='input' then the environment variable for the SerialHelper cli
option --input-write-timeout would be INPUT_WRITE_TIMEOUT.
This is particularly useful to pass cli options in IDEs that allow you to specify an environment file in a run profile
or in use with in a systemd service file's
EnvironmentFile parameter.
In the systemd service file case, there is another helper option -e/--environment which when passed into a script will
print out a list of known environment variables (which can be used for the
PassEnvironment parameter
of the systemd service file). For example in the case of a SerialHelper configured with shard='input'
the helper will print out:
Known Environment Variables: INPUT_BAUDRATE INPUT_BYTESIZE INPUT_DSRDTR INPUT_INTER_BYTE_TIMEOUT INPUT_PARITY INPUT_PORT INPUT_RTSCTS INPUT_STOPBITS INPUT_TIMEOUT INPUT_WRITE_TIMEOUT INPUT_XONXOFF
The author of the script invoking a helper may set the defaults of any parameter by passing the value into the helpers
add_parser_options method as a key word argument. For example, if you were using the SerialHelper and wanted to change
the default baudrate to 115200 you would call SerialHelper.add_parser_options like this:
SerialHelper.add_parser_options(parser, baudrate=115200)The order of precedence used to resolve the end value for a given cli option:
- The value the user of the script has entered on the command line.
- The value the user of the script passed via an environment variable.
- The value the author of the script passed as a keyword parameter to the
add_parser_options method.
This helper configures carries out a basic config for the python logging module.
It also adds another log level TRACE to python logging and adds the logger.trace method.
This helper configures all the parameters needed to configure a serial port.
The following example:
from argparse import ArgumentParser
from argparseutils.helpers.serialport import SerialHelper
def main():
parser = ArgumentParser("SerialHelper Test")
SerialHelper.add_parser_options(parser)
args = parser.parse_args()
serial_port = SerialHelper.create_serial(args)
if __name__ == '__main__':
main()when run with the --help cli option will produce:
usage: SerialHelper Test [-h] [-e] --port PORT [--baudrate BAUDRATE]
[--bytesize {5,6,7,8}]
[--parity {None,Even,Odd,Mark,Space}]
[--stopbits {1,1.5,2}] [--timeout TIMEOUT]
[--xonxoff {True,False}] [--rtscts {True,False}]
[--write-timeout WRITE_TIMEOUT]
[--dsrdtr {True,False}]
[--inter-byte-timeout INTER_BYTE_TIMEOUT]
options:
-h, --help show this help message and exit
-e, --environment Displays the known ENVIRONMENT variables that are used
as default parser options. (default: False)
--port PORT The Serial port to connect to. (default: None)
--baudrate BAUDRATE The Serial port baudrate to use. (default: 9600)
--bytesize {5,6,7,8} The number of bits for each byte. (default: 8)
--parity {None,Even,Odd,Mark,Space}
The parity algorithm to use. (default: None)
--stopbits {1,1.5,2} The number of stop bits to use. (default: 1)
--timeout TIMEOUT The read timeout to use (seconds). (default: None)
--xonxoff {True,False}
Use software flow control. (default: False)
--rtscts {True,False}
Use RTS/CTS hardware flow control. (default: False)
--write-timeout WRITE_TIMEOUT
The write timeout to use (seconds). (default: None)
--dsrdtr {True,False}
Use DSR/DTR hardware flow control. (default: False)
--inter-byte-timeout INTER_BYTE_TIMEOUT
The inter byte timeout to use. Disabled by default.
(default: None)
The following example:
from argparse import ArgumentParser
from argparseutils.helpers.serialport import SerialHelper
def main():
parser = ArgumentParser("SerialHelper Shard Test")
SerialHelper.add_parser_options(parser, shard="input")
SerialHelper.add_parser_options(parser, shard="output")
args = parser.parse_args()
serial_port = SerialHelper.create_serial(args)
if __name__ == '__main__':
main()when run with the --help cli option will produce:
usage: SerialHelper Shard Test [-h] [-e] --input-port INPUT_PORT
[--input-baudrate INPUT_BAUDRATE]
[--input-bytesize {5,6,7,8}]
[--input-parity {None,Even,Odd,Mark,Space}]
[--input-stopbits {1,1.5,2}]
[--input-timeout INPUT_TIMEOUT]
[--input-xonxoff {True,False}]
[--input-rtscts {True,False}]
[--input-write-timeout INPUT_WRITE_TIMEOUT]
[--input-dsrdtr {True,False}]
[--input-inter-byte-timeout INPUT_INTER_BYTE_TIMEOUT]
--output-port OUTPUT_PORT
[--output-baudrate OUTPUT_BAUDRATE]
[--output-bytesize {5,6,7,8}]
[--output-parity {None,Even,Odd,Mark,Space}]
[--output-stopbits {1,1.5,2}]
[--output-timeout OUTPUT_TIMEOUT]
[--output-xonxoff {True,False}]
[--output-rtscts {True,False}]
[--output-write-timeout OUTPUT_WRITE_TIMEOUT]
[--output-dsrdtr {True,False}]
[--output-inter-byte-timeout OUTPUT_INTER_BYTE_TIMEOUT]
options:
-h, --help show this help message and exit
-e, --environment Displays the known ENVIRONMENT variables that are used
as default parser options. (default: False)
--input-port INPUT_PORT
The Serial port to connect to. [input] (default: None)
--input-baudrate INPUT_BAUDRATE
The Serial port baudrate to use. [input] (default:
9600)
--input-bytesize {5,6,7,8}
The number of bits for each byte. [input] (default: 8)
--input-parity {None,Even,Odd,Mark,Space}
The parity algorithm to use. [input] (default: None)
--input-stopbits {1,1.5,2}
The number of stop bits to use. [input] (default: 1)
--input-timeout INPUT_TIMEOUT
The read timeout to use (seconds). [input] (default:
None)
--input-xonxoff {True,False}
Use software flow control. [input] (default: False)
--input-rtscts {True,False}
Use RTS/CTS hardware flow control. [input] (default:
False)
--input-write-timeout INPUT_WRITE_TIMEOUT
The write timeout to use (seconds). [input] (default:
None)
--input-dsrdtr {True,False}
Use DSR/DTR hardware flow control. [input] (default:
False)
--input-inter-byte-timeout INPUT_INTER_BYTE_TIMEOUT
The inter byte timeout to use. Disabled by default.
[input] (default: None)
--output-port OUTPUT_PORT
The Serial port to connect to. [output] (default:
None)
--output-baudrate OUTPUT_BAUDRATE
The Serial port baudrate to use. [output] (default:
9600)
--output-bytesize {5,6,7,8}
The number of bits for each byte. [output] (default:
8)
--output-parity {None,Even,Odd,Mark,Space}
The parity algorithm to use. [output] (default: None)
--output-stopbits {1,1.5,2}
The number of stop bits to use. [output] (default: 1)
--output-timeout OUTPUT_TIMEOUT
The read timeout to use (seconds). [output] (default:
None)
--output-xonxoff {True,False}
Use software flow control. [output] (default: False)
--output-rtscts {True,False}
Use RTS/CTS hardware flow control. [output] (default:
False)
--output-write-timeout OUTPUT_WRITE_TIMEOUT
The write timeout to use (seconds). [output] (default:
None)
--output-dsrdtr {True,False}
Use DSR/DTR hardware flow control. [output] (default:
False)
--output-inter-byte-timeout OUTPUT_INTER_BYTE_TIMEOUT
The inter byte timeout to use. Disabled by default.
[output] (default: None)