pool collection

direct/src/showbase/Pool.py

@@ -0,0 +1,92 @@
+"""
+
+Pool is a collection of python objects that you can checkin and
+checkout. This is useful for a cache of objects that are expensive to load
+and can be reused over and over, like splashes on cannonballs, or
+bulletholes on walls. The pool is unsorted. Items do not have to be unique
+or be the same type.
+
+Internally the pool is implemented with 2 lists, free items and used items.
+
+p = Pool([1,2,3,4,5])
+x = p.checkout()
+p.checkin(x)
+
+"""
+
+
+from direct.directnotify import DirectNotifyGlobal
+
+class Pool:
+
+    notify = DirectNotifyGlobal.directNotify.newCategory("Pool")
+    
+    def __init__(self, free=[]):
+        self.__free = free
+        self.__used = []
+
+    def add(self, item):
+        """
+        Add an item to the free list.
+        """
+        self.__free.append(item)
+
+    def remove(self, item):
+        """
+        Remove an item. Error is flagged if the item is not in the pool.
+        """
+        if item in self.__free:
+            self.__free.remove(item)
+        if item in self.__used:
+            self.__used.remove(item)
+        self.notify.error("item not in pool")
+
+    def checkout(self):
+        """
+        Get an arbitrary item from the pool.
+        """
+        if not self.__free:
+            self.notify.error("no items are free")
+        item = self.__free.pop()
+        self.__used.append(item)
+        return item
+
+    def checkin(self, item):
+        """
+        Put back a checked out item.
+        Error if the item is not checked out.
+        """
+        if item not in self.__used:
+            self.notify.error("item is not checked out")
+        self.__used.remove(item)
+        self.__free.append(item)
+
+    def reset(self):
+        """
+        Resets the pool so all items are free.
+        """
+        self.__free.extend(self.__used)
+        self.__used = []
+
+    def hasFree(self):
+        """
+        Returns true if there is at least one free item.
+        """
+        return (len(self.__free) != 0)
+
+    def isFree(self, item):
+        """
+        Returns true if this item is free for check out.
+        """
+        return (item in self.__free)
+
+    def isUsed(self, item):
+        """
+        Returns true if this item has already been checked out.
+        """
+        return (item in self.__used)
+    
+    def __repr__(self):        
+        return "free = %s\nused = %s" % (self.__free, self.__used)
+
+