Lists and Tuples

[Roy Smith]

In article <mailman.152.1070644249.16879.python-list at python.org>,
 Skip Montanaro <skip at pobox.com> wrote:

> (Probably more response than you wanted.  I kind of got carried away...)
> 
>     >> I've spent most of the day playing around with lists and tuples to
>     >> get a really good grasp on what you can do with them. I am still left
>     >> with a question and that is, when should you choose a list or a
>     >> tuple?
> 
> Generally, choose between tuples and lists based upon your data.  In
> situations where you have a small, fixed collection of objects of possibly
> differing types, use a tuple.  In situations where have a collection of
> objects of uniform type which might grow or shrink, use a list.  For
> example, an address might best be represented as a tuple:
> 
>     itcs = ("2020 Ridge Avenue", "Evanston", "IL", "60201")
>     caffe_lena = ("47 Phila Street", "Saratoga Springs", "NY", "12866")
> 
> Though all elements are actually strings, they are conceptually different
> types.

That's a good example, because it makes for a nice segue.  If you were 
holding data from a form that looked like:

Street: ___________________________
  City: ___________________________
 State: ___________________________
   Zip: ___________________________

Then I agree you're looking at a 4-tuple (assuming you didn't want to go 
whole-hog and define an Address class).  But, imagine a somewhat more 
generic form that looked like:

Address line 1: ________________________
Address line 2: ________________________
Address line 3: ________________________
Address line 4: ________________________

You might fill in exactly the same data, but now if feels like it should 
be a list.