Simulating multi-dim array problem - OR - reference confusions

[Shane Hoversten]

Hi -

	I'm doing code that needs the functionality of multi-dimensional arrays. 
  I'm getting around this right now by using lists of lists, which seems 
to work right.  For instance:

 >>> a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
 >>> b = a[0]
 >>> b[0]
1
 >>> a[0][0] = 20
 >>> b[0]
20

	This is all well and good; it seems to imply that when you say:

b = a[0]

	That b is actually a reference to the appropriate list in a, which is 
just what I need.  The problem is that I'm writing a program that needs 
to work with a chained structure.  Specifically, each element of the 
list of lists contains a "pointer" to another element in the list of 
lists.  These "pointers" can be traversed much like a linked list.  In 
other words, an "element" looks like:

[x, y, z, <PTR>]

	where <PTR> is set the way I described above, with b = a[0], or, in this 
case, a[0][3] = a[10], etc.

	Here's are my questions:

	1) Am I going to get into trouble assuming (using the example above) that 
b is basically a reference to the sublist a[0]?  I'm not clear how 
sharing works in python.

	2) Is there a way I can print out the address of a "reference"?  In 
particular I want some concise symbolic representation - like a memory 
address, or a handle id, or SOMETHING - and not a verbatim 
reconstruction of the list structure which is how python's "print" 
function does it.  If I have elements containing references to elements 
containing references to elements it's impossible to follow what's going 
on with the chain.  I'd like to have it print something like:

[[x, y, z, 0x123123], [a, b, c, 0x123958], [q, w, e, 0x358481]]

	or something to that effect, instead of interpolating and making a huge mess.

	I've tried to find references (no pun intended) to these issues but have 
come up empty.  I know the info is out there.  Can someone either tell 
me or tell me where to find it?

Thanks,

Shane