Patch #428326: New class threading.Timer.
diff --git a/Doc/lib/libthreading.tex b/Doc/lib/libthreading.tex
index 27503bd..cd77246 100644
--- a/Doc/lib/libthreading.tex
+++ b/Doc/lib/libthreading.tex
@@ -82,6 +82,10 @@
A class that represents a thread of control. This class can be safely subclassed in a limited fashion.
\end{classdesc*}
+\begin{classdesc*}{Timer}{}
+A thread that executes a function after a specified interval has passed.
+\end{classdesc*}
+
Detailed interfaces for the objects are documented below.
The design of this module is loosely based on Java's threading model.
@@ -595,3 +599,35 @@
The entire Python program exits when no active non-daemon
threads are left.
\end{methoddesc}
+
+
+\subsection{Timer Objects \label{timer-objects}}
+
+This class represents an action that should be run only after a certain amount
+of time has passed --- a timer. \class{Timer} is a subclass of \class{Thread} and
+as such also functions as an example of creating custom threads.
+
+Timers are started, as with threads, by calling their \method{start()} method. The
+timer can be stopped (before its action has begun) by calling the
+\method{cancel()} method. The interval the timer will wait before executing
+its action may not be exactly the same as the interval specified by the
+user.
+
+For example:
+\begin{verbatim}
+def hello():
+ print "hello, world"
+
+t = Timer(30.0, hello)
+t.start() # after 30 seconds, "hello, world" will be printed
+\end{verbatim}
+
+\begin{classdesc}{Timer}{interval, function, args=[], kwargs=\{\}}
+Create a timer that will run \var{function} with arguments \var{args} and
+keyword arguments \var{kwargs}, after \var{interval} seconds have passed.
+\end{classdesc}
+
+\begin{methoddesc}{cancel}{}
+Stop the timer, and cancel the execution of the timer's action. This will only
+work if the timer is still in its waiting stage.
+\end{methoddesc}
diff --git a/Lib/threading.py b/Lib/threading.py
index 268c09c..4906674 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -331,7 +331,6 @@
self.__cond.wait(timeout)
self.__cond.release()
-
# Helper to generate new thread names
_counter = 0
def _newname(template="Thread-%d"):
@@ -483,6 +482,36 @@
assert not self.__started, "cannot set daemon status of active thread"
self.__daemonic = daemonic
+# The timer class was contributed by Itamar Shtull-Trauring
+
+def Timer(*args, **kwargs):
+ return _Timer(*args, **kwargs)
+
+class _Timer(Thread):
+ """Call a function after a specified number of seconds:
+
+ t = Timer(30.0, f, args=[], kwargs={})
+ t.start()
+ t.cancel() # stop the timer's action if it's still waiting
+ """
+
+ def __init__(self, interval, function, args=[], kwargs={}):
+ Thread.__init__(self)
+ self.interval = interval
+ self.function = function
+ self.args = args
+ self.kwargs = kwargs
+ self.finished = Event()
+
+ def cancel(self):
+ """Stop the timer if it hasn't finished yet"""
+ self.finished.set()
+
+ def run(self):
+ self.finished.wait(self.interval)
+ if not self.finished.isSet():
+ self.function(*self.args, **self.kwargs)
+ self.finished.set()
# Special thread class to represent the main thread
# This is garbage collected through an exit handler
diff --git a/Misc/NEWS b/Misc/NEWS
index 5e763c0..a4d7395 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -81,6 +81,9 @@
Library
+- Asynchronous timeout actions are available through the new class
+ threading.Timer.
+
- math.log and math.log10 now return sensible results for even huge
long arguments. For example, math.log10(10 ** 10000) ~= 10000.0.