Function isatty

invoke/util.py:97–127

Cleanly determine whether ``stream`` is a TTY. Specifically, first try calling ``stream.isatty()``, and if that fails (e.g. due to lacking the method entirely) fallback to `os.isatty`. .. note:: Most of the time, we don't actually care about true TTY-ness, but mere

(stream: IO)

def isatty(stream: IO) -> Union[bool, Any]:
    """
    Cleanly determine whether ``stream`` is a TTY.

    Specifically, first try calling ``stream.isatty()``, and if that fails
    (e.g. due to lacking the method entirely) fallback to `os.isatty`.

    .. note::
        Most of the time, we don't actually care about true TTY-ness, but
        merely whether the stream seems to have a fileno (per `has_fileno`).
        However, in some cases (notably the use of `pty.fork` to present a
        local pseudoterminal) we need to tell if a given stream has a valid
        fileno but *isn't* tied to an actual terminal. Thus, this function.

    :param stream: A file-like object.

    :returns:
        A boolean depending on the result of calling ``.isatty()`` and/or
        `os.isatty`.

    .. versionadded:: 1.0
    """
    # If there *is* an .isatty, ask it.
    if hasattr(stream, "isatty") and callable(stream.isatty):
        return stream.isatty()
    # If there wasn't, see if it has a fileno, and if so, ask os.isatty
    elif has_fileno(stream):
        return os.isatty(stream.fileno())
    # If we got here, none of the above worked, so it's reasonable to assume
    # the darn thing isn't a real TTY.
    return False


def helpline(obj: object) -> Optional[str]: