.. currentmodule:: click
Click makes it very easy to document your command line tools. First of all, it automatically generates help pages for you. While these are currently not customizable in terms of their layout, all of the text can be changed.
Commands and options accept help arguments. In the case of commands, the docstring of the function is automatically used if provided.
Simple example:
.. click:example::
@click.command()
@click.option('--count', default=1, help='number of greetings')
@click.argument('name')
def hello(count, name):
"""This script prints hello NAME COUNT times."""
for x in range(count):
click.echo('Hello %s!' % name)
And what it looks like:
.. click:run::
invoke(hello, args=['--help'])
Arguments cannot be documented this way. This is to follow the general convention of Unix tools of using arguments for only the most necessary things and to document them in the introduction text by referring to them by name.
The default behavior of Click is to rewrap text based on the width of the terminal. In some circumstances, this can become a problem. The main issue is when showing code examples, where newlines are significant.
Rewrapping can be disabled on a per-paragraph basis by adding a line with
solely the \b escape marker in it. This line will be removed from the
help text and rewrapping will be disabled.
Example:
.. click:example::
@click.command()
def cli():
"""First paragraph.
This is a very long second paragraph and as you
can see wrapped very early in the source text
but will be rewrapped to the terminal width in
the final output.
\b
This is
a paragraph
without rewrapping.
And this is a paragraph
that will be rewrapped again.
"""
And what it looks like:
.. click:run::
invoke(cli, args=['--help'])
Click gets command help text from function docstrings. However if you already use docstrings to document function arguments you may not want to see :param: and :return: lines in your help text.
You can use the \f escape marker to have Click truncate the help text
after the marker.
Example:
.. click:example::
@click.command()
@click.pass_context
def cli(ctx):
"""First paragraph.
This is a very long second
paragraph and not correctly
wrapped but it will be rewrapped.
\f
:param click.core.Context ctx: Click context.
"""
And what it looks like:
.. click:run::
invoke(cli, args=['--help'])
Options and parameters accept a metavar argument that can change the
meta variable in the help page. The default version is the parameter name
in uppercase with underscores, but can be annotated differently if
desired. This can be customized at all levels:
.. click:example::
@click.command(options_metavar='<options>')
@click.option('--count', default=1, help='number of greetings',
metavar='<int>')
@click.argument('name', metavar='<name>')
def hello(count, name):
"""This script prints hello <name> <int> times."""
for x in range(count):
click.echo('Hello %s!' % name)
Example:
.. click:run::
invoke(hello, args=['--help'])
For commands, a short help snippet is generated. By default, it's the first sentence of the help message of the command, unless it's too long. This can also be overridden:
.. click:example::
@click.group()
def cli():
"""A simple command line tool."""
@cli.command('init', short_help='init the repo')
def init():
"""Initializes the repository."""
@cli.command('delete', short_help='delete the repo')
def delete():
"""Deletes the repository."""
And what it looks like:
.. click:run::
invoke(cli, prog_name='repo.py')
.. versionadded:: 2.0
The help parameter is implemented in Click in a very special manner.
Unlike regular parameters it's automatically added by Click for any
command and it performs automatic conflict resolution. By default it's
called --help, but this can be changed. If a command itself implements
a parameter with the same name, the default help parameter stops accepting
it. There is a context setting that can be used to override the names of
the help parameters called :attr:`~Context.help_option_names`.
This example changes the default parameters to -h and --help
instead of just --help:
.. click:example::
CONTEXT_SETTINGS = dict(help_option_names=['-h', '--help'])
@click.command(context_settings=CONTEXT_SETTINGS)
def cli():
pass
And what it looks like:
.. click:run::
invoke(cli, ['-h'])