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Nuiitivet Documentation

Thread Safety

Observable: Thread Safety

Problem

Updating an Observable from a worker thread can trigger UI updates outside the UI thread.

# worker thread
viewmodel.data.value = result
# UI subscriber may crash if callback touches UI directly

Solution: `.dispatch_to_ui()`

Use .dispatch_to_ui() for observables that drive UI rendering.

import threading
from nuiitivet.observable import Observable

class ViewModel:
    data = Observable([])

    def __init__(self):
        self.data.dispatch_to_ui()

    def load_async(self):
        def worker():
            result = fetch_data()
            self.data.value = result

        threading.Thread(target=worker).start()

Default Behavior

Without .dispatch_to_ui(), notifications run in the current thread for lower overhead. This is suitable for pure logic-layer computations.

Chain Placement

.dispatch_to_ui() can appear before or after other operators.

total = (
    price
    .combine(quantity)
    .compute(lambda p, q: p * q)
    .dispatch_to_ui()
)

Important Constraints

Inside compute/mapping functions:

✅ use observable values
❌ avoid direct UI widget access

# good
text = count.map(lambda c: f"Count: {c}")

# then update widgets in subscribe callbacks
text.subscribe(lambda value: set_label_text(value))

Next Steps