Python optparse metavar смотреть онлайн

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optparse is a python module that allows you to easily parse command-line arguments in your scripts. the metavar parameter in optparse is used to specify the placeholder text for command-line arguments when displaying usage messages. it provides clarity to users about the expected input for each option. in this tutorial, we'll explore how to use metavar with optparse and provide code examples to illustrate its usage.
to get started, you need to import the optparse module in your python script:
next, you need to create an optionparser object. this object will be used to define and parse command-line options and arguments.
you can define command-line options using the add_option method of the optionparser object. when defining options, you can specify the metavar parameter to set the placeholder text for the option's argument.
here's the syntax for defining an option with metavar:
in this example, -f and --file are the short and long option names, respectively. dest specifies the destination variable for the option's value, and metavar sets the placeholder text to "file."
after defining your options, you need to parse the command-line arguments using the parse_args() method:
this method will return two values: options and args. options will be a namespace object containing the option values, and args will be a list of positional arguments.
to display usage messages with the specified metavar placeholders, you can use the parser.print_help() method:
here's a complete example that demonstrates how to use metavar with optparse:
in this example, when you run the script with the -h or --help option, it will display a usage message with the metavar placeholders:
when you provide values for the -f and -o options, the script will access and display those values.
that's it! you now know how to use the metavar parameter in optparse to set placeholder text for command-line arguments, making your script's usage messages more informative and user-friendly.
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