github.com/apache/beam/sdks/v2@v2.48.2/python/apache_beam/coders/observable.py (about)

     1  #
     2  # Licensed to the Apache Software Foundation (ASF) under one or more
     3  # contributor license agreements.  See the NOTICE file distributed with
     4  # this work for additional information regarding copyright ownership.
     5  # The ASF licenses this file to You under the Apache License, Version 2.0
     6  # (the "License"); you may not use this file except in compliance with
     7  # the License.  You may obtain a copy of the License at
     8  #
     9  #    http://www.apache.org/licenses/LICENSE-2.0
    10  #
    11  # Unless required by applicable law or agreed to in writing, software
    12  # distributed under the License is distributed on an "AS IS" BASIS,
    13  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14  # See the License for the specific language governing permissions and
    15  # limitations under the License.
    16  #
    17  
    18  """Observable base class for iterables.
    19  
    20  For internal use only; no backwards-compatibility guarantees.
    21  """
    22  # pytype: skip-file
    23  
    24  
    25  class ObservableMixin(object):
    26    """For internal use only; no backwards-compatibility guarantees.
    27  
    28    An observable iterable.
    29  
    30    Subclasses need to call self.notify_observers with any object yielded.
    31    """
    32    def __init__(self):
    33      self.observers = []
    34  
    35    def register_observer(self, callback):
    36      self.observers.append(callback)
    37  
    38    def notify_observers(self, value, **kwargs):
    39      # self.observers is almost always empty
    40      if self.observers:
    41        for o in self.observers:
    42          o(value, **kwargs)