State sharing between Python and Javascript

[r0x0r]

The next major version of pywebview will introduce state - a way to seamlessly share data between Python and Javascript. State is represented by the pywebview.state object in Javascript and Window.state object in Python. Updating a property on either object will update its value on the other side. An example can be found here.

Additionally, each state object emits an event when state is updated. Implementation details are not set in stone, but currently the syntax is pywebview.state.addEventHandler('change', handler) and window.state += lambda event_type, key, value: pass

State is implemented by means of a proxy in Javascript and an observable class in Python.

The current ahem state can be tracked in the store branch

Ideas, suggestions or questions are welcomed

[r0x0r]

As far as I am concerned, basic implementation is done now. Latest changes are pushed into the 6.0 branch.

One limitation of the current version is that it detects changes only on the window.state object itself and mutations of the objects are not registered. Ie this will trigger a state update window.state.counter = 1 and this will not

window.state.nested_counter = {
   'counter': 0
}
window.state.nested_counter['counter'] = 1 # this goes undetected

I have attempted to solve this with two different approaches

1. By converting dicts and lists to observable versions, which detect and propagate changes. The implementation turned out rather complicated and I could not get it fully working. Besides I am not exactly sure if it is a good approach to convert user data be default
2. By making State object assignable and introducing sub-states. Something like this

sub_state = State({'counter': 0})
window.state.nested_counter = sub_state
sub_state.counter = 1 # this will be detected

Sub-states have exactly same API as the main state

Anyhow neither of these approaches are implemented, nor will be for the 6.0. It remains to be seen if this feature is needed.

Another feature that might be introduced in the future is global state, a state object which can be shared between different windows.