Observe Example

Demonstration of the use of static and dynamic observers.

Tip

To see this example in action, download it from observe and run:

$ python observe.py

Example Atom Code

#------------------------------------------------------------------------------
# Copyright (c) 2013-2017, Nucleic Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file LICENSE, distributed with this software.
#------------------------------------------------------------------------------
"""Demonstration of the use of static and dynamic observers.

"""
from __future__ import (division, unicode_literals, print_function,
                        absolute_import)

from atom.api import Atom, Str, Range, Typed, observe


class Dog(Atom):

    name = Str()


class Person(Atom):
    """ A simple class representing a person object.

    """
    name = Str()

    age = Range(low=0)

    dog = Typed(Dog, ())

    def _observe_age(self, change):
        print('Age changed: {0}'.format(change['value']))

    @observe('name')
    def any_name_i_want(self, change):
        print('Name changed: {0}'.format(change['value']))

    @observe('dog.name')
    def another_random_name(self, change):
        print('Dog name changed: {0}'.format(change['value']))


def main():
    bob = Person(name='Robert Paulson', age=40)
    bob.name = 'Bobby Paulson'
    bob.age = 50
    bob.dog.name = 'Scruffy'

    def watcher_func(change):
        print('Watcher func change: {0}'.format(change['value']))

    bob.observe('age', watcher_func)
    bob.age = 51
    bob.unobserve('age', watcher_func)
    bob.age = 52  # No call to watcher func


if __name__ == '__main__':
    main()