The chain of responsibility pattern inside Python allows us to build an application with loose coupling in mind. This is achieved by passing a received request through a chain of objects inside the software.

The following code snippet shows the implementation of the chain of responsibility pattern inside Python:

import abc

class Handler(metaclass=abc.ABCMeta):
    """Handler provides an interface to build handlers."""

    def __init__(self, handler=None):
        """Initialize the handler.

        Keyword arguments:
        handler -- The next handler object to be called
        """

        self._next_handler = handler

    @abc.abstractmethod
    def handler(self, data):
        """The handler abstract method.

        Keyword arguments:
        data -- The data to be processed by the handler
        """

        pass

class StringHandler(Handler):
    """String type object handler."""

    def handler(self, data):
        if type(data) is str:
            print("Stringt type data found.")
        elif self._next_handler is not None:
            self._next_handler.handler(data)
        else:
            raise Exception("Unable to find a suitable handler for data.")

class IntegerHandler(Handler):
    """Integer type object handler."""

    def handler(self, data):
        if type(data) is int:
            print("Integer type data found")
        elif self._next_handler is not None:
            self._next_handler.handler(data)
        else:
            raise Exception("Unable to find a suitable handler for data.")

if __name__ == '__main__':
    int_handler = IntegerHandler()
    str_handler = StringHandler(int_handler)
    str_handler.handler(2)