very good reasons?

[Bjorn Pettersen]

Grant Griffin wrote:
> 
> Hi Gang,
> 
> I was trying to chain "sort" and "reverse" together the other day <<confess>>,
> ala Perl, but I found that it didn't work, e.g.:
> 
>    Python 2.0b2 (#6, Sep 26 2000, 14:59:21) [MSC 32 bit (Intel)] on win32
>    >>> a=[1,2,3,4]
>    >>> b=a.sort().reverse()
>    Traceback (most recent call last):
>      File "<stdin>", line 1, in ?
>    AttributeError: 'None' object has no attribute 'reverse'
>    >>> c=a.sort()
>    >>> repr(c)
>    'None'
> 
> I would have expected sort and reverse to return the list in question, but
> instead they return None.

That's because sort is inefficient on very big lists (it takes over
9/100 seconds to sort a 20,000 item list of floating point numbers!).
Since we know it's so slow, we wouldn't want you to write code like "for
i in a.sort()" without having to jump through some loops... It's the
same reason why shelves don't have an items() method.

<wink?>
-- bjorn