Посредник (Controller, Mediator)

Посредник (Controller)
Поведенческий паттерн проектирования позволяет разлепить связи между классами и берет на себя функцию связывания. Классы будут общаться через класс-посредник.

Пример реализации паттерна Посредник на python

# coding: utf-8


class WindowBase(object):
    def show(self):
        raise NotImplementedError()

    def hide(self):
        raise NotImplementedError()


class MainWindow(WindowBase):
    def show(self):
        print 'Show MainWindow'

    def hide(self):
        print 'Hide MainWindow'


class SettingWindow(WindowBase):
    def show(self):
        print 'Show SettingWindow'

    def hide(self):
        print 'Hide SettingWindow'


class HelpWindow(WindowBase):
    def show(self):
        print 'Show HelpWindow'

    def hide(self):
        print 'Hide HelpWindow'


class WindowMediator(object):
    def __init__(self):
        self.windows = dict.fromkeys(['main', 'setting', 'help'])

    def show(self, win):
        for window in self.windows.itervalues():
            if not window is win:
                window.hide()
        win.show()

    def set_main(self, win):
        self.windows['main'] = win

    def set_setting(self, win):
        self.windows['setting'] = win

    def set_help(self, win):
        self.windows['help'] = win


main_win = MainWindow()
setting_win = SettingWindow()
help_win = HelpWindow()

med = WindowMediator()
med.set_main(main_win)
med.set_setting(setting_win)
med.set_help(help_win)

main_win.show()  # Show MainWindow

med.show(setting_win)
# Hide MainWindow
# Hide HelpWindow
# Show SettingWindow

med.show(help_win)
# Hide MainWindow
# Hide SettingWindow
# Show HelpWindow