philiprehberger-debounce 0.4.0

Debounce and throttle decorators for Python functions.

philiprehberger-debounce

Debounce and throttle decorators for Python functions.

Installation

pip install philiprehberger-debounce

Usage

from philiprehberger_debounce import debounce, throttle

Debounce

Delay execution until a quiet period has passed. Each new call resets the timer.

@debounce(0.5)
def on_resize(width, height):
    print(f"Resized to {width}x{height}")

on_resize(800, 600)
on_resize(1024, 768)  # cancels the previous call
# Only the last call executes after 0.5s

Bounded debounce

Use max_wait to guarantee the function fires at most max_wait seconds after the first pending call, even if calls keep arriving and continuously reset the debounce timer. Mirrors lodash debounce({ maxWait }) semantics.

@debounce(0.5, max_wait=2.0)
def autosave(content):
    print(f"Saving: {content[:20]}...")

# Even with continuous edits, autosave fires at least every 2s.
for chunk in stream_keystrokes():
    autosave(chunk)

max_wait must be positive and >= seconds; otherwise ValueError is raised.

Cancel and flush

The wrapper exposes .cancel() (drop any pending trailing call) and .flush() (fire it immediately). Mirrors the lodash debounce control API.

@debounce(0.5)
def save(content):
    print(f"saving {content}")

save("draft 1")
save.cancel()       # drop the pending call
save("draft 2")
save.flush()        # fire immediately, don't wait for the timer

Throttle

Limit a function to a fixed number of calls within a time window. Excess calls are silently dropped.

@throttle(calls=3, per=1.0)
def send_request(data):
    print(f"Sending {data}")

for i in range(10):
    send_request(i)  # only the first 3 calls within 1s execute

API

Decorator	Parameter	Description
debounce(seconds, *, leading=False, max_wait=None)	seconds	Minimum quiet period (in seconds) before the function is invoked. Each new call cancels the previous pending invocation and restarts the timer.
	leading	If True, fire on the leading edge of the window instead of the trailing edge. Subsequent rapid calls are suppressed until seconds of silence have elapsed.
	max_wait	Optional upper bound (in seconds) on how long the function may be deferred from the first pending call. Must be positive and >= seconds. Mirrors lodash debounce({ maxWait }).
wrapper.cancel()	—	Discard any pending trailing invocation and reset leading-edge state.
wrapper.flush()	—	Fire the pending trailing invocation immediately (no-op if none is pending).
throttle(calls, per)	calls	Maximum number of allowed invocations within the sliding window.
	per	Length of the sliding window in seconds. Calls beyond calls within per are silently dropped.

Development

pip install -e .
python -m pytest tests/ -v

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License

MIT