terminal.py 文件源码

def cbreak(self):
        """
        Allow each keystroke to be read immediately after it is pressed.

        This is a context manager for :func:`tty.setcbreak`.

        This context manager activates 'rare' mode, the opposite of 'cooked'
        mode: On entry, :func:`tty.setcbreak` mode is activated disabling
        line-buffering of keyboard input and turning off automatic echo of
        input as output.

        .. note:: You must explicitly print any user input you would like
            displayed.  If you provide any kind of editing, you must handle
            backspace and other line-editing control functions in this mode
            as well!

        **Normally**, characters received from the keyboard cannot be read
        by Python until the *Return* key is pressed. Also known as *cooked* or
        *canonical input* mode, it allows the tty driver to provide
        line-editing before shuttling the input to your program and is the
        (implicit) default terminal mode set by most unix shells before
        executing programs.

        Technically, this context manager sets the :mod:`termios` attributes
        of the terminal attached to :obj:`sys.__stdin__`.

        .. note:: :func:`tty.setcbreak` sets ``VMIN = 1`` and ``VTIME = 0``,
            see http://www.unixwiz.net/techtips/termios-vmin-vtime.html
        """
        if HAS_TTY and self._keyboard_fd is not None:
            # Save current terminal mode:
            save_mode = termios.tcgetattr(self._keyboard_fd)
            save_line_buffered = self._line_buffered
            tty.setcbreak(self._keyboard_fd, termios.TCSANOW)
            try:
                self._line_buffered = False
                yield
            finally:
                # Restore prior mode:
                termios.tcsetattr(self._keyboard_fd,
                                  termios.TCSAFLUSH,
                                  save_mode)
                self._line_buffered = save_line_buffered
        else:
            yield