language design question

[Steven Bethard]

Terry Reedy wrote:
> "Gregory Guthrie" <guthrie at mum.edu> wrote in message 
> news:1152465029_31209 at sp6iad.superfeed.net...
>>   - why is len() not a member function of strings? Instead one says 
>> len(w).
> 
> Consider
>>>> map(len, ('abc', (1,2,3), [1,2], {1:2}))
> [3, 3, 2, 1]
> 
> Now try to rewrite this using methods (member functions).

For all the doubters out there, here's an example you can't really 
rewrite with a list comprehension::

     >>> sorted(['aaa', 'bb', 'c'])
     ['aaa', 'bb', 'c']
     >>> sorted(['aaa', 'bb', 'c'], key=len)
     ['c', 'bb', 'aaa']

If len() were a method of string objects, you could try using the 
unbound method and writing this as::

     >>> sorted(['aaa', 'bb', 'c'], key=str.len)
     ['c', 'bb', 'aaa']

But then your code would break on lists that weren't strings.

STeVe