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A debounce function decorator in Python similar to the one in underscore.js, tested with 2.7
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from threading import Timer | |
def debounce(wait): | |
""" Decorator that will postpone a functions | |
execution until after wait seconds | |
have elapsed since the last time it was invoked. """ | |
def decorator(fn): | |
def debounced(*args, **kwargs): | |
def call_it(): | |
fn(*args, **kwargs) | |
try: | |
debounced.t.cancel() | |
except(AttributeError): | |
pass | |
debounced.t = Timer(wait, call_it) | |
debounced.t.start() | |
return debounced | |
return decorator |
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import unittest | |
import time | |
from debounce import debounce | |
class TestDebounce(unittest.TestCase): | |
@debounce(10) | |
def increment(self): | |
""" Simple function that | |
increments a counter when | |
called, used to test the | |
debounce function decorator """ | |
self.count += 1 | |
def setUp(self): | |
self.count = 0 | |
def test_debounce(self): | |
""" Test that the increment | |
function is being debounced. | |
The counter should only be incremented | |
once 10 seconds after the last call | |
to the function """ | |
self.assertTrue(self.count == 0) | |
self.increment() | |
self.increment() | |
time.sleep(9) | |
self.assertTrue(self.count == 0) | |
self.increment() | |
self.increment() | |
self.increment() | |
self.increment() | |
self.assertTrue(self.count == 0) | |
time.sleep(10) | |
self.assertTrue(self.count == 1) | |
if __name__ == '__main__': | |
unittest.main() |
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