[Tutor] Initializing Tupples

[Joseph J. Strout]

At 7:46 PM +0000 08/27/99, Jonathon wrote:

>	Let's see if I understand the difference between lists and
>	tuples.
>
>	Once a Tuple is created, it can not be changed.
>	Once a List is created, both it, and its contents can
>	be changed --- increased, decreased etc.

Yep, that's it.  (And, for the record, strings are just like tuples.)

>	Example_Tuple = ( "joe", "curly", "moe" )
>	and Example_Tuple retains that value for the duration
>	of the program.

Well, not exactly -- you could easily rebind Example_Tuple to 
something else, e.g.:

    Example_Tuple = Example_Tuple[:2]      # keep only the first two items
or
    Example_Tuple = Example_Tuple + ("larry", "guido")  # append two items


These work because the slice operator [:] or the addition operator 
creates a *new* tuple, rather than modifying the old one in place; 
and then this new tuple is bound to the name "Example_Tuple".  Does 
this make sense?

Cheers,
-- Joe

,------------------------------------------------------------------.
|    Joseph J. Strout           Biocomputing -- The Salk Institute |
|    joe@strout.net             http://www.strout.net              |
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