Maintaining a list

[Josiah Carlson]

Thomas Philips wrote:

> I'm teaching myself programming using Python and want to build a list
> inside a function (rather like using a static variable in a Fortran
> subroutime - the list must not disappear as soon as the subroutine is
> exited). What's the simplest way to do this?
[snip]
> The list must be initialized to an empty list before the first call,
> and must be preserved between calls. I have not got to object oriented
> programming as yet, so please keep the solution simple.

Work your way through these interactions.

 >>> def myrutine(x, mylist=[]):
...     mylist.append(x)
...     print mylist
...
 >>> myrutine(1)
[1]
 >>> myrutine(2)
[1, 2]
 >>> myrutine(10)
[1, 2, 10]
 >>> b = []
 >>> myrutine(1, b)
[1]
 >>> b
[1]
 >>> myrutine(8)
[1, 2, 10, 8]
 >>> b
[1]
 >>>

One thing you need to remember is that list.append() returns None, not a 
new list.

  - Josiah