sunetos · July 6, 2011 21:07 · Jul 6, 2011 · Jul 6, 2011
diff --git a/gistfile1.py b/gistfile1.py
@@ -18,9 +18,9 @@ def get_id(self):
         if len(self.ids_free) > 0:
             return self.ids_free.pop()
 
-        self.last_id = id = self.new_id(self.last_id)
-        self.ids_in_use.add(id)
-        return id
+        self.last_id = id_ = self.new_id(self.last_id)
+        self.ids_in_use.add(id_)
+        return id_
 
     def release_id(self, the_id):
         if the_id in self.ids_in_use:

diff --git a/gistfile1.py b/gistfile1.py
@@ -0,0 +1,37 @@
+__author__ = 'Adam R. Smith'
+
+class IDPool(object):
+    '''
+    Create a pool of IDs to allow reuse. The "new_id" function generates the next
+    valid ID from the previous one. If not given, defaults to incrementing an integer.
+    '''
+
+    def __init__(self, new_id=None):
+        if new_id is None: new_id = lambda x: x + 1
+
+        self.ids_in_use = set()
+        self.ids_free = set()
+        self.new_id = new_id
+        self.last_id = 0
+
+    def get_id(self):
+        if len(self.ids_free) > 0:
+            return self.ids_free.pop()
+
+        self.last_id = id = self.new_id(self.last_id)
+        self.ids_in_use.add(id)
+        return id
+
+    def release_id(self, the_id):
+        if the_id in self.ids_in_use:
+            self.ids_in_use.remove(the_id)
+            self.ids_free.add(the_id)
+
+if __name__ == '__main__':
+    pool = IDPool()
+    for i in xrange(5):
+        print 'got id: %d' % pool.get_id()
+    print 'releasing id 3'
+    pool.release_id(3)
+    print 'got id: %d' % pool.get_id()
+    print 'got id: %d' % pool.get_id()