indexing

	description:

		"[
			Abstract subsystem that can be enabled and disabled.
		]"

	date: "$Date$"
	revision: "$Revision$"

deferred class EM_SUBSYSTEM

inherit

	EM_CONSTANTS
		export {NONE} all end

	EM_SHARED_SUBSYSTEMS
		export {NONE} all end

	SDL_FUNCTIONS_EXTERNAL
		export {NONE} all end

	DISPOSABLE
		export {NONE} all end

feature -- Status report

	is_enabled: BOOLEAN is
			-- Is the subsystem enabled?
		deferred
		end

feature -- Subsystem management

	enable is
			-- Enable subsystem.
		require
			not_enabled: not is_enabled
		deferred
		end

	disable is
			-- Disable subsystem.
		require
			enabled: is_enabled
		deferred
		end

feature {NONE} -- Implementation

	dispose is
			-- Free external resources.
		do
			if is_enabled then
				disable
			end
		end

end