# Copyright 2016 Matteo Franchin
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

class BackCaller(object):
    def __init__(self, **callbacks):
        self.callbacks = dict(**callbacks)

    def set_callback(self, name, callback):
        if name not in self.callbacks:
            raise ValueError('Unknown callback name \'{}\''.format(name))
        self.callbacks[name] = callback

    def call(self, name, *args):
        '''Call one of the available callbacks, passing the provided arguments.
        '''
        if name not in self.callbacks:
            raise ValueError('Unknown callback name \'{}\''.format(name))
        cb = self.callbacks[name]
        if cb is not None:
            return cb(*args)
