subclassing built-in types

[Gabriel Cooper]

I have data in lists of dictionaries with an accompanying array that I
would like to be able to treat as a normal array of strings so that it
will work with predefined functions that work with such, but I would
also like to have the ability to add and manipulate attributes, such as
each field's padding for output of the corresponding data:

(Running on RHFC2)

Python 2.3.3 (#1, May 7 2004, 10:31:40)
[GCC 3.3.3 20040412 (Red Hat Linux 3.3.3-7)] on linux2
[...]
IDLE 1.0.2[color=blue][color=green][color=darkred]
>>> class myString(str):[/color][/color][/color]
def __init__(self, thestring, padding=0, *args,**kargs):
str.__init__(se lf,thestring, *args,**kargs)
self.padding = padding

[color=blue][color=green][color=darkred]
>>> x = myString("hello ")
>>> x[/color][/color][/color]
'hello'[color=blue][color=green][color=darkred]
>>> x.padding[/color][/color][/color]
0[color=blue][color=green][color=darkred]
>>> x = myString("hello ",40)[/color][/color][/color]

Traceback (most recent call last):
File "<pyshell#205>" , line 1, in -toplevel-
x = myString("hello ",40)
TypeError: str() takes at most 1 argument (2 given)[color=blue][color=green][color=darkred]
>>> x = myString("hello ")
>>> x.padding = 50
>>> x[/color][/color][/color]
'hello'[color=blue][color=green][color=darkred]
>>> x.padding[/color][/color][/color]
50[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

(in other words, I can do it in two steps, not one. I also tried
UserString and string as superclasses.)