Simple Cache - improvements?

[rav at smo3k.z.pl]

Hello,
Below is very simple cache implementation. There is no LRU, MRU,
no predictor or other features. Nothing but cache.
I'm interested in improvements to this code. It could
be useful - not only for me, I hope :-)
Rafal Smotrzyk

#code-start
import whrandom

class MSimpleCache:
   def __init__(self,agetfunc,amaxlen=100):
      self.GetValue=agetfunc
      self.MaxLen=amaxlen
      self.VDict={}
      self.KDict={}
      self.VPos=1
      self.AccessRatio=0
      self.HitRatio=0
   def __getitem__(self,key):
      self.AccessRatio=self.AccessRatio+1
      id=self.KDict.get(key,0)
      if id:
         self.HitRatio=self.HitRatio+1
         return self.VDict[id][1]
      else:
         v=self.VDict.get(self.VPos,0)
         if v:
            del self.KDict[v[0]]
         ret=self.GetValue(key)
         self.VDict[self.VPos]=[key,ret]
         self.KDict[key]=self.VPos
         self.VPos=self.VPos+1
         if self.VPos>self.MaxLen:
            self.VPos=1
         return ret
   def dump(self):
      print 'Access ratio:',self.AccessRatio
      print 'Hit ratio:',self.HitRatio
      print 'Hit %:',100.0*self.HitRatio/self.AccessRatio
      print 'VDict len:',len(self.VDict.keys())
      print 'KDict len:',len(self.KDict.keys())

# cached operation - sample
def GetCalculatedValue(key):
   x=`key`+'aaaa'
   y=key*0.5
   z=x+`y`
   return z

# models of distribution max=1000 def GetLinear(key):  return key def
GetRandom(key):  return whrandom.randint(1,max)
l1,l2,l3=whrandom.randint(1,max),whrandom.randint(1,max),whrandom.randint(1,m
ax) def GetNDist(key):	global l1,l2,l3 
l1,l2,l3=l2,l3,whrandom.randint(1,max)	return int((l1+l2+l3)/3)

#test...
for aname,afunc in
[['Linear',GetLinear],['Random',GetRandom],['NDist',GetNDist]]:
   acache=MSimpleCache(GetCalculatedValue,250)
   for i in range(1000):
      k=afunc(i)
      x=acache[k]
      y=GetCalculatedValue(k)
      if x!=y:
         print 'ValueError:',k,x,y
   print 'Name:',aname
   acache.dump()
   print

#code-end

#output-start
Name: Linear
Access ratio: 1000
Hit ratio: 0
Hit %: 0.0
VDict len: 250
KDict len: 250

Name: Random
Access ratio: 1000
Hit ratio: 221
Hit %: 22.1
VDict len: 250
KDict len: 250

Name: NDist
Access ratio: 1000
Hit ratio: 355
Hit %: 35.5
VDict len: 250
KDict len: 250
#output-end

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