glue-viz / echo

Callback Properties in Python

echo: Callback Properties in Python

Echo is a small library for attaching callback functions to property state changes. For example:

class Switch(object):
    state = CallbackProperty('off')

def report_change(state):
    print 'the switch is %s' % state

s = Switch()
add_callback(s, 'state', report_change)

s.state = 'on'  # prints 'the switch is on'

CalllbackProperties can also be built using decorators

class Switch(object):

      @callback_property
      def state(self):
        return self._state

      @state.setter
      def state(self, value):
          if value not in ['on', 'off']:
              raise ValueError("invalid setting")
          self._state = value

Full documentation is avilable here

echo's Issues

Avoid circular callbacks between properties and Qt widgets

When setting a value for a slider from a property, the slider shouldn't re-adjust the property based on the discretization of the slider, as this can then cause additional callbacks.

Add documentation for Qt functionality

Migrate CI to GitHub Actions

We should migrate the CI from Azure Pipelines to GitHub actions - and once this is done we can address #30 (in a separate PR).

Add ability to delay/ignore specific callback functions

with ignore_callback(instance, property, callback_function):
    pass

Add Python 3.11 and 3.12 to CI

@dhomeier - would you be able to look into this?

delay_callback and ignore_callback should work for global callbacks

Currently these do not delay/ignore callbacks for global callbacks

Test against PyQt6/PySide6

We should make sure that we test against PyQt6 and PySide6 now that these are released.