#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Author: Andreas Büsching <crunchy@bitkipper.net>
#
# a generic dispatcher implementation
#
# $Id$
#
# Copyright 2006
#	Andreas Büsching <crunchy@bitkipper.net>
#
# This library is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version
# 2.1 as published by the Free Software Foundation.
#
# This library is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA

"""generic implementation of external dispatchers, integratable into
several notifiers."""

# required for dispatcher use
MIN_TIMER = 100

__dispatchers = []

def dispatcher_add( method ):
    """The notifier supports external dispatcher functions that will be called
    within each scheduler step. This functionality may be usful for
    applications having an own event mechanism that needs to be triggered as
    often as possible. This method registers a new dispatcher function. To
    ensure that the notifier loop does not suspend to long in the sleep state
    during the select a minimal timer MIN_TIMER is set to guarantee that the
    dispatcher functions are called at least every MIN_TIMER milliseconds."""
    global __dispatchers
    __dispatchers.append( method )

def dispatcher_remove( method ):
    """Removes an external dispatcher function from the list"""
    global __dispatchers
    if method in __dispatchers:
        __dispatchers.remove( method )

def dispatcher_run():
    global __dispatchers
    if not __dispatchers:
        return
    for disp in __dispatchers[:]:
        if not disp():
            dispatcher_remove( disp )

def dispatcher_count():
    return len(__dispatchers)
