Python click 模块，help_option() 实例源码

def common_options(*args, **kwargs):
    """
    This is a multi-purpose decorator for applying a "base" set of options
    shared by all commands.
    It can be applied either directly, or given keyword arguments.

    Usage:

    >>> @common_options
    >>> def mycommand(abc, xyz):
    >>>     ...

    or

    >>> @common_options(no_format_option=True)
    >>> def mycommand(abc, xyz):
    >>>     ...
    """
    def decorate(f, **kwargs):
        """
        Work of actually decorating a function -- wrapped in here because we
        want to dispatch depending on how `common_options` is invoked
        """
        f = version_option(f)
        f = debug_option(f)
        f = verbose_option(f)
        f = click.help_option('-h', '--help')(f)

        # if the format option is being allowed, it needs to be applied to `f`
        if not kwargs.get('no_format_option'):
            f = format_option(f)

        # if the --map-http-status option is being allowed, ...
        if not kwargs.get('no_map_http_status_option'):
            f = map_http_status_option(f)

        return f

    return detect_and_decorate(decorate, args, kwargs)

def extended_help_option(extended_help=None, *param_decls, **attrs):
    """
    Based on the click.help_option code.

    Adds a ``--extended-help`` option which immediately ends the program
    printing out the extended extended-help page. Defaults to using the
    callback's doc string, but can be given an explicit value as well.

    This is intended for use as a decorator on a command to provide a 3rd level
    of help verbosity suitable for use as a manpage (though not formatted as such explicitly).

    Like :func:`version_option`, this is implemented as eager option that
    prints in the callback and exits.

    All arguments are forwarded to :func:`option`.
    """

    def decorator(f):
        def callback(ctx, param, value):
            if value and not ctx.resilient_parsing:
                if not extended_help:
                    ctx.command.help = ctx.command.callback.__doc__
                    click.echo(ctx.get_help(), color=ctx.color)
                else:
                    ctx.command.help = extended_help
                    click.echo(ctx.get_help(), color=ctx.color)
                ctx.exit()

        attrs.setdefault('is_flag', True)
        attrs.setdefault('expose_value', False)
        attrs.setdefault('help', 'Show extended help content, similar to manpage, and exit.')
        attrs.setdefault('is_eager', True)
        attrs['callback'] = callback
        return click.option(*(param_decls or ('--extended-help',)), **attrs)(f)

    return decorator

def get_command(self, ctx, name):
        ns = {}
        fn = os.path.join(command_folder, name + '.py')
        try:
            with open(fn) as f:
                code = compile(f.read(), fn, 'exec')
                eval(code, ns, ns)
            return ns[name]
        except IOError:
            click.help_option()

# base help message