pystorex 0.2.0

A Python state management library inspired by NgRx

Pystorex

A lightweight Python state management library inspired by NgRx/Redux patterns and ReactiveX for Python (reactivex). Manage application state with reducers, handle side effects with effects, compose middleware, and select state slices efficiently.

---

Features

• Typed State: Define your root state using Pydantic or any Python object, fully generic.
• Reducers: Pure functions to update state in response to actions.
• Effects: Handle side effects by listening to action streams and optionally dispatching actions.
• Middleware: Insert custom logic (logging, thunks, error handling) into dispatch pipeline.
• Selectors: Memoized and configurable (deep compare, TTL) state accessors.
• Immutable Updates: Shallow copy at feature level or integrate with immutables.Map.
• Hot Module Management: Register/unregister feature reducers and effects at runtime.

---

Installation

pip install pystorex

Requires Python 3.7+

---

Quick Start

import time
from typing import Optional
from pydantic import BaseModel
from reactivex import operators as ops

from pystorex.actions import create_action
from pystorex import create_store, create_reducer, on, create_effect
from pystorex.store_selectors import create_selector
from pystorex.middleware import LoggerMiddleware

# 1. 定義狀態模型
class CounterState(BaseModel):
    count: int = 0
    loading: bool = False
    error: Optional[str] = None
    last_updated: Optional[float] = None

# 2. 定義 Actions
increment = create_action("increment")
decrement = create_action("decrement")
reset = create_action("reset", lambda value: value)
increment_by = create_action("incrementBy", lambda amount: amount)

load_count_request = create_action("loadCountRequest")
load_count_success = create_action("loadCountSuccess", lambda value: value)
load_count_failure = create_action("loadCountFailure", lambda error: error)

# 3. 定義 Reducer
def counter_handler(state: CounterState, action) -> CounterState:
    new_state = state.copy(deep=True)
    now = time.time()

    if action.type == increment.type:
        new_state.count += 1
        new_state.last_updated = now
    elif action.type == decrement.type:
        new_state.count -= 1
        new_state.last_updated = now
    elif action.type == reset.type:
        new_state.count = action.payload
        new_state.last_updated = now
    elif action.type == increment_by.type:
        new_state.count += action.payload
        new_state.last_updated = now
    elif action.type == load_count_request.type:
        new_state.loading = True
        new_state.error = None
    elif action.type == load_count_success.type:
        new_state.loading = False
        new_state.count = action.payload
        new_state.last_updated = now
    elif action.type == load_count_failure.type:
        new_state.loading = False
        new_state.error = action.payload

    return new_state

counter_reducer = create_reducer(
    CounterState(),
    on(increment, counter_handler),
    on(decrement, counter_handler),
    on(reset, counter_handler),
    on(increment_by, counter_handler),
    on(load_count_request, counter_handler),
    on(load_count_success, counter_handler),
    on(load_count_failure, counter_handler),
)

# 4. 定義 Effects
class CounterEffects:
    @create_effect
    def load_count(self, action_stream):
        return action_stream.pipe(
            ops.filter(lambda action: action.type == load_count_request.type),
            ops.do_action(lambda _: print("Effect: Loading counter...")),
            ops.delay(1.0),
            ops.map(lambda _: load_count_success(42))
        )


# 5. 建立 Store、註冊模組
store = create_store()
store.apply_middleware(LoggerMiddleware)
store.register_root({"counter": counter_reducer})
store.register_effects(CounterEffects)

# 6. 訂閱狀態與測試
get_counter_state = lambda state: state["counter"]
get_count = create_selector(
    get_counter_state,
    result_fn=lambda counter: counter.count or 0
)
store.select(get_count).subscribe(
    lambda c: print(f"Count: {c[1]}")
)

# 7. 執行操作示例
if __name__ == "__main__":
    store.dispatch(increment())
    store.dispatch(increment_by(5))
    store.dispatch(decrement())
    store.dispatch(reset(10))
    store.dispatch(load_count_request())
    # 給 Effects 一些時間
    time.sleep(2)

---

Examples

This project includes the following example scripts to demonstrate both the modular and monolithic usage patterns:

Counter Example

• examples/counter_example/main.py: Entry point for the modular Counter example.
• examples/counter_example/counter_example_monolithic.py: Monolithic Counter example.

Detection Example

• examples/detection_example/main.py: Entry point for the modular Detection example.
• examples/detection_example/detection_example_monolithic.py: Monolithic Detection example.

You can run them from the project root:

python examples/counter_example/main.py
python examples/counter_example/counter_example_monolithic.py
python examples/detection_example/main.py
python examples/detection_example/detection_example_monolithic.py

Core Concepts

Store

Manages application state, dispatches actions, and notifies subscribers.

store = create_store(MyRootState())
store.register_root({
    "feature_key": feature_reducer,
    # ... more reducers
})
store.register_effects(FeatureEffects)

Actions

Use create_action(type, prepare_fn) to define action creators.

from pystorex.actions import create_action
my_action = create_action("myAction", lambda data: {"payload": data})

Reducers

Pure functions taking (state, action) and returning new state.

from pystorex import create_reducer, on
reducer = create_reducer(
    InitialState(),
    on(my_action, my_handler)
)

Effects

Side-effect handlers listening to action streams via ReactiveX.

from pystorex import create_effect
from reactivex import operators as ops

class FeatureEffects:
    @create_effect
    def log_actions(action$):
        return action$.pipe(
            ops.filter(lambda a: a.type == my_action.type),
            ops.map(lambda _: another_action())
        )

Middleware

Insert custom dispatch logic. Example: Logger

class LoggerMiddleware:
    def on_next(self, action): print("▶️", action.type)
    def on_complete(self, result, action): print("✅", action)
    def on_error(self, err, action): print("❌", err)

store.apply_middleware(LoggerMiddleware)

Selectors

Memoized accessors with optional deep=True or ttl.

from pystorex.selectors import create_selector
get_items = create_selector(
    lambda s: s.feature.items,
    result_fn=lambda items: [i.value for i in items],
    deep=True, ttl=5.0
)

---

Advanced Topics

• Hot Module DnD: store.register_feature / store.unregister_feature to add/remove features at runtime.
• Immutable State: Integrate immutables.Map for structural sharing.
• DevTools: Capture action/state history for time-travel debugging.

---

Publishing to PyPI

1. Ensure pyproject.toml & setup.cfg are configured.
2. Install build tools:

   pip install --upgrade build twine
   

3. Build distributions:

   python -m build
   

4. Upload:

   python -m twine upload dist/*
   

---

Contributing

• Fork the repo
• Create a feature branch
• Write tests (pytest) and update docs
• Submit a Pull Request

---

License

MIT