Module: add timer support to modules

modules that want to create a timer should implement timer_interval()
to return a non-zero value (the timer interval, in seconds) and
timer_do() (the method that does stuff)

Module.py

@@ -22,6 +22,7 @@ import inspect
 import re
 import sys
 import sqlite3
+from threading import Timer
 
 from extlib import irclib
 
@@ -31,6 +32,11 @@ class Module(object):
     def priority(self):
         return 50
 
+    def timer_interval(self):
+        """Run a timer-based event every N seconds (0 to disable)."""
+
+        return 0
+
     def __init__(self, irc, config, server):
         """Construct a feature module. Inheritors can do special things here, but
         should be sure to call Module.__init__.
@@ -54,6 +60,10 @@ class Module(object):
         # set up database for this module
         self.db_init()
 
+        # register the timer, if the implementing module has one
+        if self.timer_interval() > 0:
+            Timer(self.timer_interval(), self.timer_bootstrap, ()).start()
+
         # print what was loaded, for debugging
         print("loaded " + self.__class__.__name__)
 
@@ -216,6 +226,26 @@ class Module(object):
 
         print("looks like someone forgot to implement do!")
 
+    def timer_bootstrap(self):
+        """Run a thread that does something periodically.
+
+        This only has real functionality if timer_interval() is
+        defined to return non-zero.
+        """
+
+        # don't actually do stuff if, since the last timer registration,
+        # the interval was set to 0
+        if self.timer_interval() > 0:
+            self.timer_do()
+
+        if self.timer_interval() > 0:
+            Timer(self.timer_interval(), self.timer_bootstrap, ()).start()
+
+    def timer_do(self):
+        """If we're invoking the timer, do something (that you should implement)."""
+
+        print("looks like someone forgot to implement timer_do!")
+
     def help_description(self):
         """Return a quick list of commands or other summary, should be
         less than two lines. If you want the module hidden from "!help",