appending to a list via properties

[Carl Banks]

Lonnie Princehouse wrote:
> Here's a curious hack I want to put up for discussion.  I'm thinking of
> writing a PEP for it.

A minor library change wouldn' t need a PEP.

> Observation
> -----------------
> I found myself using this construct for assembling multiple lists:
>
>     foo = []
>     qux = []
>
>     while some_condition:
>        a, b = calculate_something()
>        foo.append(a)
>        qux.append(b)
>
> Not elegant!

I don't agree; however:

>     class better_list (list):
>         tail = property(None, list.append)

This is an impressive, spiffy little class.

> Well?

I suspect it's too sneaky and not commonly useful enough to get serious
consideration for the standard library.  But definitely submit it to
Python Cookbook:
http://aspn.activestate.com/ASPN/Python/Cookbook/

Carl Banks


P.S. to get rid of temporary variables while using regular lists:

growing_lists = foo,qux
while some_condition:
    for (s,x) in zip(growing_list,calculate_something()):
        list.append(s,x)

No I don't really recommend it.