cpython/Tools/pynche/Switchboard.py

"""Switchboard class.

This class is used to coordinate updates among all Viewers.  Every Viewer must
conform to the following interface:

    - it must include a method called update_yourself() which takes three
      arguments; the red, green, and blue values of the selected color.

    - When a Viewer selects a color and wishes to update all other Views, it
      should call update_views() on the Switchboard object.  Not that the
      Viewer typically does *not* update itself before calling update_views(), 
      since this would cause it to get updated twice.
"""

class Switchboard:
    def __init__(self, colordb):
        self.__views = []
        self.__colordb = colordb
        self.__red = 0
        self.__green = 0
        self.__blue = 0

    def add_view(self, view):
        self.__views.append(view)

    def update_views(self, red, green, blue):
        self.__red = red
        self.__green = green
        self.__blue = blue
        for v in self.__views:
            v.update_yourself(red, green, blue)

    def update_views_current(self):
        self.update_views(self.__red, self.__green, self.__blue)

    def colordb(self):
        return self.__colordb