Python 3.0 - is this true?

["Martin v. Löwis"]

> def comp(x1, x2):
>    try:
>        if x1<x2:
>            return -1
>        else:
>            return 1
>    except TypeError:
>        if str(x1)<str(x2):
>            return -1
>        else:
>            return 1
> 

Please correct me if I'm wrong, but I think this is not transitive. If
strings and ints are uncomparable, this will give you 20 < "5" and
"5" < 8, but not 20 < 8. As a result, quicksort will do nonsense
with that comparison function (i.e. it won't guarantee that things
are sorted in increasing order)

> Not sure how to transform it into a search key that is efficient and
> reliable.

Depending on what your notion of "sameness of lists" is, the following
might do:

def key(o):
    return id(type(o)),o

This only requires that all objects of the same type in the list can
be sorted. If this is not guaranteed, then

def key(o)
    try:
        o<o
        return id(type(o)),o
    except TypeError:
        return id(type(o)),id(o)

might do.

Regards,
Martin