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<title>Scheduling tasks for the future</title>
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<h1>Scheduling tasks for the future</h1>
<p>Let's say we want to run a task X seconds in the future.
The way to do that is defined in the reactor interface <code
class="API">twisted.internet.interfaces.IReactorTime</code>:</p>
<pre class="python">
from twisted.internet import reactor
def f(s):
print "this will run 3.5 seconds after it was scheduled: %s" % s
reactor.callLater(3.5, f, "hello, world")
</pre>
<p>If we want a task to run every X seconds repeatedly, we can
use <code
class="API">twisted.internet.task.LoopingCall</code>:</p>
<pre class="python">
from twisted.internet import task
def runEverySecond():
print "a second has passed"
l = task.LoopingCall(runEverySecond)
l.start(1.0) # call every second
# l.stop() will stop the looping calls
</pre>
<p>If we want to cancel a task that we've scheduled:</p>
<pre class="python">
from twisted.internet import reactor
def f():
print "I'll never run."
callID = reactor.callLater(5, f)
callID.cancel()
</pre>
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