Local variables in classes and class instantiation

[A.J. Bonnema]

Hi all,

I just started using Python. I used to do some Java programming, so I am 
not completely blank.

I have a small question about how classes get instantiated within other 
classes. I have added the source of a test program to the bottom of this 
mail, that contains 3 methods within a testclass that each instantiate 
the same class and bind it to a local variable. My understanding was, 
that the local variable gets garbage collected as soon as the method 
goes out of scope. Thus I would expect the local variable 'cpu' in these 
methods to be independant and create different instances of the class CPU.

Still, when I execute all three methods, I get two instances that are 
equal and the third is different.
Is there some circomstance that makes two object creations result in the 
same object?

============================================================= output
Output from the (test)program is:
cpu class = <cpu.CPU instance at 0x8244eec>
.cpu class = <cpu.CPU instance at 0x8244eec>
.cpu class = <cpu.CPU instance at 0x8244f0c>
.
----------------------------------------------------------------------
Ran 3 tests in 0.001s

OK
=============================================================== source
The source of the test program is:

import sys
import unittest
from cpu import CPU

class cpuAddEntries(unittest.TestCase):
     def testEmptyCPU(self):
         "Test empty CPU."
         expected="{}"
         cpu = CPU("cpu01")
         print "cpu class = "+repr(cpu)
         result = cpu.showTimes()
         self.assertEquals(expected,result)
     def testOneEntry(self):
         "Test one entry into CPU"
         time = "0000"
         expected="{'%s': ('user', 'system')}" % time
         cpu = CPU("cpu02")
         print "cpu class = "+repr(cpu)
         cpu.addMetric (time, "user", "system")
         result = cpu.showTimes()
         self.assertEquals(expected,result)
     def testDuplicate(self):
         "Test inserting a duplicate entry."
         global exceptions
         time = "0000"
         expected="{'%s': ('user', 'system')}" % time
         cpu = CPU("cpu03")
         print "cpu class = "+repr(cpu)
         cpu.addMetric (time, "user", "system")
         self.assertRaises(Exception, cpu.addMetric, time, "user1", 
"system1")

if __name__ == "__main__":
     unittest.main()

-- 
A.J. Bonnema, Leiden The Netherlands,
user #328198 (Linux Counter http://counter.li.org)