Question

Assume I have a class A with a overriden hash method that returns some user-defined integer:

class A:
   def __init__(self,hash):
      self.hash = hash

   def __hash__(self):
      return self.hash

   def __cmp__(self,other):
      return cmp(self.hash,other.hash)

Now, at any given point in time, I’d like to have only one object with the same hash, so I maintain a set s that contains such objects of class A. My problem is the following:

s = {A(1234)} 
a = A(1234)

if a in s:
   # then assign the corresponding object in set s to a

How can I achieve this?

Thanks!

Answer 1

Don’t use a set, use a dictionary (which is also a set, in a sense).

objects = {}
a = A(1234)
if a.hash in objects:
    a = objects[a.hash]
objects[a.hash] = a