Reactive state management for Python
Project description
Observ 👁
Observ is a Python port of Vue.js' computed properties and watchers. It is completely event loop/framework agnostic and has no dependencies so it can be used in any project targeting Python >= 3.6.
Observ provides the following two benefits for stateful applications:
- You no longer need to manually invalidate and recompute state (e.g. by dirty flags):
- computed state is invalidated automatically
- computed state is lazily re-evaluated
- You can react to changes in state (computed or not), enabling unidirectional flow:
- state changes lead to view changes (e.g. a state change callback updates a UI widget)
- the view triggers input events (e.g. a mouse event is triggered in the UI)
- input events lead to state changes (e.g. a mouse event updates the state)
API
from observ import observe, computed, watch
state = observe(state)
Observe nested structures of dicts, lists, tuples and sets. Returns an observable clone of the state input object.
watcher = watch(func, callback, deep=False, immediate=False)
React to changes in the state accessed in func with callback(old_value, new_value). Returns a watcher object. delelete it to disable the callback.
wrapped_func = computed(func)
Define computed state based on observable state with func and recompute lazily. Returns a wrapped copy of the function which only recomputes the output if any of the state it depends on becomes dirty. Can be used as a function decorator.
Quick start and example
Install observ with pip/pipenv/poetry:
pip install observ
Check out examples/observe_qt.py for a simple example using observ.
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