Class Option

src/click/core.py:2791–3528

Options are usually optional values on the command line and have some extra features that arguments don't have. All other parameters are passed onwards to the parameter constructor. :param show_default: Show the default value for this option in its help text. Values are not sho

class Option(Parameter):
    """Options are usually optional values on the command line and
    have some extra features that arguments don't have.

    All other parameters are passed onwards to the parameter constructor.

    :param show_default: Show the default value for this option in its
        help text. Values are not shown by default, unless
        :attr:`Context.show_default` is ``True``. If this value is a
        string, it shows that string in parentheses instead of the
        actual value. This is particularly useful for dynamic options.
        For single option boolean flags, the default remains hidden if
        its value is ``False``.
    :param show_envvar: Controls if an environment variable should be
        shown on the help page and error messages.
        Normally, environment variables are not shown.
    :param prompt: If set to ``True`` or a non empty string then the
        user will be prompted for input. If set to ``True`` the prompt
        will be the option name capitalized. A deprecated option cannot be
        prompted.
    :param confirmation_prompt: Prompt a second time to confirm the
        value if it was prompted for. Can be set to a string instead of
        ``True`` to customize the message.
    :param prompt_required: If set to ``False``, the user will be
        prompted for input only when the option was specified as a flag
        without a value.
    :param hide_input: If this is ``True`` then the input on the prompt
        will be hidden from the user. This is useful for password input.
    :param is_flag: forces this option to act as a flag.  The default is
                    auto detection.
    :param flag_value: which value should be used for this flag if it's
                       enabled.  This is set to a boolean automatically if
                       the option string contains a slash to mark two options.
    :param multiple: if this is set to `True` then the argument is accepted
                     multiple times and recorded.  This is similar to ``nargs``
                     in how it works but supports arbitrary number of
                     arguments.
    :param count: this flag makes an option increment an integer.
    :param allow_from_autoenv: if this is enabled then the value of this
                               parameter will be pulled from an environment
                               variable in case a prefix is defined on the
                               context.
    :param help: the help string.
    :param hidden: hide this option from help outputs.
    :param attrs: Other command arguments described in :class:`Parameter`.

    .. versionchanged:: 8.4.0
        Non-basic ``flag_value`` types (not ``str``, ``int``, ``float``, or
        ``bool``) are passed through unchanged instead of being stringified.
        Previously, ``type=click.UNPROCESSED`` was required to preserve them.

    .. versionchanged:: 8.2
        ``envvar`` used with ``flag_value`` will always use the ``flag_value``,
        previously it would use the value of the environment variable.

    .. versionchanged:: 8.1
        Help text indentation is cleaned here instead of only in the
        ``@option`` decorator.