bizarre Recursive/class interaction

[Bob Roberts]

The following code gives me an assertion error from the line
assert( not ret.data)
which means that some how ret.data is getting set to something besides
an empty list.  I don't see how this can happen since nothing is
passed into the construction of ret and ret.data defaults to an empty
list.


import UserList

def JunkRecursive(line):
    print line
    gotH = 0
    ret = MyClass()
    assert( not ret.data)
    i = 0
    while i < len(line):
        char = line[i]
        print char
        if char == "a":
            ret.append(1)
        elif char == "h":
            if not gotH:
                gotH = 1
            else:
                subList = JunkRecursive(line[i:])
                ret.append(subList)
        i += 1
    return ret

class MyClass(UserList.UserList):
    pass
    def __init__(self, data = []):
        UserList.UserList.__init__(self)
        self.data = data
        if self.data:
            print self.data


line = "haaah"
JunkRecursive(line)




This gives the output:
haaah
h
a
a
a
h
h
[1, 1, 1]
Traceback (most recent call last):
  File "junk.py", line 33, in ?
    JunkRecursive(line)
  File "junk.py", line 18, in JunkRecursive
    subList = JunkRecursive(line[i:])
  File "junk.py", line 7, in JunkRecursive
    assert( not ret.data)
AssertionError