Docopt is a command line interface description module. It helps you define a interface for a command-line application and generates parser for it. The interface message in docopt is a formalized help message.
You can install docopt module in various ways, pip is one of the best ways to install docopt.
$pip install docopt
Note: docopt is tested with Python 2.5, 2.6, 2.7, 3.2, 3.3 and PyPy as well.
docopt is most commonly used to display the help messages and it is invoked with -h or –help option. You can import and call this module with the following command.
Parameters of the module is as shown below :
- doc : It is a docstring (__doc__) that contains the help message.
- argv : It is an optional argument vector contains list of strings.
- version : It is an optional argument mentioning the version of the program.
- help : Responsible for displaying the help message. It is True by default.
- options_first : This doesn’t allow the mixing of positional arguments and optional arguments. By default it is False.
docopt gives you strong control over your help page and it consists of the usage keyword which is case-insensitive that is followed by your program_name. A usage pattern can be described with various elements as mentioned below :
< argument > argument : The element starting with “<” and ending with “>” is called a positional argument. It is position sensitive.
–option -o: The element starting with “–” or “-” are called as long or short option. It can either be mentioned as
-h, --help Display help -o, --option Display options -l, --all List all -q, --quit exit --version Version 3.6.1
[optional argument] : The element starting with “[” and ending with “]” is called an optional argument. It is considered optionally.
< argument >… : The ellipsis “…” is used when the element present to the left can be repeated more than once.
(required arguments) : The elements starting with “(” and ending with “)” is a required element.
(--option1 | --option2) says that either of –option1 or –option2 is required.
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