Help understanding the decisions *behind* python?

Piet van Oostrum piet at
Tue Jul 21 17:05:36 CEST 2009

>>>>> Hendrik van Rooyen <hendrik at> (HvR) wrote:

>HvR> On Monday 20 July 2009 21:26:07 Phillip B Oldham wrote:
>>> On Jul 20, 6:08 pm, Duncan Booth < at invalid.invalid> wrote:
>>> > The main reason why you need both lists and tuples is that because a
>>> > tuple of immutable objects is itself immutable you can use it as a
>>> > dictionary key.
>>> Really? That sounds interesting, although I can't think of any real-
>>> world cases where you'd use something like that.

>HvR> simplest is something like a point in the cartesian plane with
>HvR> an associated attribute like colour.

There are numerous other examples. Anytime you need a key that is not a
single object but composed of more than one:
Name + birthday
Street + number + City
Student + Course
Piet van Oostrum <piet at>
URL: [PGP 8DAE142BE17999C4]
Private email: piet at

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