Comparisons of incompatible types

[Ben Finney]

Carl Banks <pavlovevidence at gmail.com> writes:

> On Dec 6, 4:17 pm, Steven D'Aprano <steve
> +comp.lang.pyt... at pearwood.info> wrote:
> > Nevertheless, I agree that in hindsight, the ability to sort such
> > lists is not as important as the consistency of comparisons.
>
> I think that feeling the need to sort non-homogenous lists is
> indictative of bad design.

It can also be indicative of code written for a Python that doesn't have
sets.

Comparing two list objects to see whether they have the same items in
any sequence can be done with::

    set(foolist) == set(barlist)

but, if there is no ‘set’ type, it's fine to write::

    sorted(foolist) == sorted(barlist)

So there's no design error in wanting heterogenerous sequences to sort;
it can be quite Pythonic (until the advent of the ‘set’ type).

And, of course, that code needs to continue to work in Python 2.x;
hence, the comparison of incompatible types cannot be fixed without
breaking backward compatibility. Hence it's not fixed until Python 3.x.

-- 
 \        “All opinions are not equal. Some are a very great deal more |
  `\    robust, sophisticated and well supported in logic and argument |
_o__)                                     than others.” —Douglas Adams |
Ben Finney